摘要： An exploding wire system has been used to examine the effects of microstructure on the dynamic fracture behavior of high purity iron, 0.2% C steel and free machining steels. Optical and scanning electron microscopy studies of the fractured specimens indicate that the dynamic loading response is strongly material dependent, being inlfuenced by the grain size and the presence of brittle second phase particles. Predominantly intergranular microcracks are observed in pure iron specimens having grain sizes ranging from 40 to 200 microns, whereas transgranular microcracks are observed to initiate the fracture process in 0.2% C steel of varying microstructures. The degree of dynamic fracture increases with increasing grain size in 0.2% C steel containing ferrite - pearlite microstructures. A detailed study of dynamically loaded specimens indicates that the occurrence of microfractures in 0.2% C steel is associated with second phase particles in the form of inclusions and carbides, and that the predominance of intergranular cracking in pure iron is due to its relatively low carbon content and coarse grain size. The fracture characteristics of the various materials are compared and discussed in relation to the dynamic fracture behavior of steel subjected to other methods of loading.

关键词： 显微结构   干涉   彩色照片   石墨化   碳素材料  

摘要： 在碳素材料的理化检验中,研究碳素材料的显微结构的特征具有重要的意义。本文介绍部分碳素材料在灵敏色调(色干涉)下的显微结构的彩色照片,并以此来说明它们的结构特征。试验条件:应用大型卧式金相显微镜(Neophoto),光源采用碳棒弧光源,经紫外滤光器,并用RI灵敏色片产生灵敏色调照明,采用国产GB—17°彩色胶卷摄照,彩色正片采用放大印制法。试样制备接一般金相试样的要求,经磨制、粗抛和精抛光而成,对于粉状、粒状及结构

关键词： Neurosecretion   Harvestman   Exocytosis   Release   Ultrastructure  

摘要： The paraganglionic plates of the harvestman, Trogulus, are neurohemal organs composed of a thick neural lamella facing a blood sinus, basal glial cells, and seven distinct types of axon terminals (A1, A2, B1, B2, B3, B4 and C) identified on the basis of elementary granule size, electron density, and structure of *** release of A1 type granules occurs by exocytosis into the extraaxonal space below the acellular neural lamella. The release of the content of C granules occurs after fragmentation into small electron dense vesicles. Clusters of these vesicles intermixed with clear vesicles pressing against the axolemma beneath the neural lamella, apparantly correspond to the sites of release.

关键词： Rare earths   Lanthanides   Recycling   Extractive metallurgy   Magnets   Catalysts   BatteriesPreview | Abstract | Full Text | PDF (449 KB) | FiguresNovember 18   2013G A MoldoveanuG A Moldoveanu   V G PapangelakisV G PapangelakisMoldoveanuMoldoveanu   PapangelakisPapangelakisMoldoveanu et al.Moldoveanu et al.Leaching of lanthanides from various weathered elution deposited oresLeaching of lanthanides from various weathered elution deposited oresG A MoldoveanuG A Moldoveanu   V G PapangelakisV G PapangelakisMoldoveanuMoldoveanu   PapangelakisPapangelakisMoldoveanu et al.Moldoveanu et al.Volume: 52   Issue: 3   pp. 257–264http://***/10.1179/1879139513Y.0000000060Keywords: Ion adsorption clays   Rare earths leaching   Rare earths desorption   Ion exchange leaching   Lanthanides   Rare earth elements Preview | Abstract | Full Text | PDF (314 KB) | FiguresNovember 18   2013D K ChibweD K Chibwe   G AkdoganG Akdogan   C AldrichC Aldrich   P TaskinenP TaskinenChibweChibwe   AkdoganAkdogan   AldrichAldrich   TaskinenTaskinenChibwe et al.Chibwe et al.Modelling of mixing   mass transfer and phase distribution in a Peirce–Smith converter modelModelling of mixing   mass transfer and phase distribution in a Peirce–Smith converter modelD K ChibweD K Chibwe   G AkdoganG Akdogan   C AldrichC Aldrich   P TaskinenP TaskinenChibweChibwe   AkdoganAkdogan   AldrichAldrich   TaskinenTaskinenChibwe et al.Chibwe et al.Volume: 52   Issue: 2   pp. 176–189http://***/10.1179/1879139512Y.0000000056Keywords: Computational fluid dynamics   Peirce–Smith converter   ModellingPreview | Abstract | Full Text | PDF (536 KB) | FiguresNovember 22   2013D K ChibweD K Chibwe   G AkdoganG Akdogan   C AldrichC Aldrich   P TaskinenP TaskinenChibweChibwe   AkdoganAkdogan   AldrichAldrich   TaskinenTaskinenChibwe et al.Chibwe et al.Modelling of mixing   mass transfer and phase distribution in a Peirce–Smith converter modelModelling of mixing   mass transfer and phase distribution in a Peirce–Smith converter modelD K ChibweD K Chibwe   G AkdoganG Akdogan   C AldrichC Aldrich   P TaskinenP TaskinenChibweChibwe   AkdoganAkdogan   AldrichAldrich   TaskinenTaskinen  

摘要： Polycrystalline materials are visualized in this paper as a statistical ensemble of microelements whose crystallographic axes are randomly, but not uniform randomly, oriented in the material system. Based on this concept the influence of internal dislocations and grain boundaries on the elastic response of such metals is discussed. The latter influence is taken into consideration by combining the grain boundary coincidence cell models of Bollmann with the relaxation technique of Weins in the case of symmetric tilt boundaries. The micromechanics theory of Axelrad and Provan is also briefly discussed to indicate where these quantitative metallurgical studies are of importance in the further development of this theory. Résumé Dans cette étude, les matériaux poly cristallins sont considérés comme un ensemble statistique de micro-éléments dont les axes cristallographiques sont orientés au hasard, mais non uniformément, dans le matériau. A partir de ce concept, les auteurs discutent de l'influence de dislocation et des joints de grains sur la réponse élastique de tels métaux. L'influence des joints de grains est considérée en combinant le modéle des sites en coincidence de Bollmann avec la technique de relaxation de Weins, pour le cas des joints de flexion symétriques. La théorie de la micromécanique de Axelrad et Provan est aussi brièvement discutée pour indiquer quelles sont les études métallurgiques quantitatives nécessaires au développement ultérieur de cette théorie.

关键词： Public Health   Collagen   Sodium   Basement Membrane   Cataract  

摘要： The peripheral exfoliation band was scraped from seventeen lenses that were removed because of senile cataract. A suspension of the exfoliation substance, negatively stained with sodium silicotungstate, was studied and compared with the sectioned exfoliation *** is concluded that the exfoliation substance probably consists of a collagen material, that perhaps comes from basement membranes.

摘要： Polymer nanocomposites (PNCs) represent a radical alternative to conventional filled polymers or polymer blends. In contrast to conventional composites, where the in- cluded phase is on the order of micrometers, PNCs are defined as those that have discrete constituents on the order of a few hundred nanometers. The value of PNCs is not solely based on tailoring mechanical properties, as in traditional composite design and manufacture, but rather on the potential for the design and optimization of multi-functional properties. There is major interest in these polymeric materials embedded with a conductive nanoscale filler. This is due to the possibility of design- ing a composite that retains the easy processing of plastics but can take advantage of a conductive nanoscale phase; providing electrical conductivity in additional to structural reinforcement. The challenge to modeling multi-functional properties of PNCs is that, tradition- ally, different models have been applied to model different properties. Mechanical properties are most often modeled using mean-field models from micromechanics; properties depend on the microstructural arrangement of the included phase, phase properties and volume fraction. Electrical conductivity has primarily been modeled using percolation theory and power-law models; properties depend on theoretical or simulation based estimates of a percolation threshold, phase properties and volume fraction. However, models of both properties should ideally be built on specific mi- crostructural descriptions as well as include a probabilistic framework to capture percolation effects. In this work a modeling framework, developed for predicting composite mechan- ical properties, is investigated for its applicability in modeling effective electrical composite properties. The basis for using a micromechanics approach for predictions of conductivity is presented as well as how the model is adapted to model conductiv- ity. A comparison of the adapted and

关键词： 纳米   拉曼光谱   均方根键角畸变   平均键畸变能   Nano-material   GaP   Gallium Phosphide   Raman Spectra   Root mean square bond angle distribution   Mean stored energy  

摘要： 利用纳米GaP固体材料拉曼光谱的类横向光学模峰移(ΔωTO)对其均方根键角畸变(Δθ)和平均键畸变能(Uθ)进行了计算.计算结果表明:当成型压力增加时,纳米GaP固体材料的Δθ和Uθ均增加;而将纳米GaP固体材料在325℃进行1h热处理后,其Δθ和Uθ并没有明显的变化.关键词

关键词： 微机电器件   红外光谱   纳米级   石墨微结构   MEMS device   infrared spectroscopy   nanoscale   graphite microstructure  

摘要： 具有原子级光滑平面的石墨平台微结构是实现特殊功能微机电器件、微系统的重要基础。石墨微结构的化学信息表征对微机电器件、微系统的制备及性能有着重要的意义。先使用原子力显微镜获得形貌信息，再使用纳米级红外光谱对微结构的不同区域进行表征，获得了多个特征位置的红外光谱。通过对红外光谱的分析发现相对于其他位置，石墨平台表面具有非常有序的碳六元环结构，并且吸附的水分子最少。而石墨平台微结构的边缘由于悬键及微加工等原因是吸附水分子最多的位置，石墨基底由于微加工的破坏已经不具有碳六元环结构。这些信息为了解微结构的化学状态提供了帮助，明确所处环境对石墨平台微结构不同位置的影响，能够指导微机电器件的制备与应用。关键词

关键词： 微晶玻璃   氧化亚铜纳米晶   显微结构   抗菌性能   可见光催化   glass-ceramics   Cu2O nanocrystalline   microstructure   antibacterial property   visible light driven photocatalysis  

摘要： 新型Cu2O纳米微晶玻璃具有高Cu载量、低成本和易大规模制备等特点，有望成为载银抗菌玻璃较有潜力的替代者。通过采用XRD、Raman光谱、XPS、FESEM和TEM等表征方法重点研究了不同ZnO/K2O比对SiO2-Al2O3-K2O-ZnO-P2O5-B2O3-CuO微晶玻璃显微结构的影响，并分析讨论了其结构-性能关系。结果表明，微晶玻璃中Zn与P元素会富集在Cu元素所在区域的附近，适量的ZnO能使微晶玻璃中析出的Cu2O晶粒尺寸稳定在纳米级别，并能调节微晶玻璃中Cu元素的浸出速率。Cu2O纳米微晶玻璃对大肠杆菌和金黄色葡萄球菌均具有显著的抗菌效果，并能实现对维多利亚蓝B溶液的可见光催化降解，是一种极具发展潜力的新型功能微晶玻璃材料。

关键词： 溶剂交换   异丙醇   丙酮   甲醇   乙醇   微结构   solvent exchange   isopropanol   acetone   methanol   ethanol   microstructure  

摘要： 溶剂交换法广泛应用于水泥基材料的干燥和终止水化中。本文综述了溶剂交换对水泥浆体显微结构的影响。阐述了交换参数(样品尺寸、液-固比、交换时间和去除方法)的选取原则。重点论述了常见交换溶剂(异丙醇、丙酮、甲醇和乙醇)与水泥水化产物(氢氧化钙、水化硅酸钙和钙矾石)之间存在的物理化学反应。在交换参数和溶剂的影响下，对比分析了水泥基材料的孔结构参数(孔隙率和孔径分布)。最后提出了溶剂交换方法目前存在的问题及研究展望。