InP-based RTD/HEMT monolithic integration

Monolithic integration of resonant tunneling diodes (RTDs) and high electron mobility transistors (HEMTs) is an important development direction of ultra-high speed integrated circuit. A kind of top-RTD and bottom-HEMT material structure is epitaxied on InP substrate through molecular beam epitaxy. Based on wet chemical etching, metal lift-off and air bridge interconnection technology, RTD and HEMT are fabricated simultaneously. The peak-to-valley current ratio of RTD is 7.7 and the peak voltage is 0.33 V at room temperature. The pinch-off voltage is -0.5 V and the current gain cut-frequency is 30 GHz for a 1.0 μm gate length depletion mode HEMT. The two devices are conformable in current magnitude, which is suitable for the construction of various RTD/HEMT monolithic integration logic circuits.     

Genetically encoded X-ray cellular imaging for nanoscale protein localization

Spatial resolution defines the physical limit of microscopes for probing biomolecular localization and interactions in cells. Whereas synchrotron-based X-ray microscopy (XRM) represents a unique approach for imaging a whole cell with nanoscale resolution due to its intrinsic nanoscale resolution and great penetration ability, existing approaches to label biomolecules rely on the use of exogenous tags that are multi-step and error-prone. Here, we repurpose engineered peroxidases as genetically encoded X-ray-sensitive tags (GXET) for site-specific labeling of protein-of-interest in mammalian cells. We find that 3,3^′-diaminobenzidine (DAB) polymers that are in-situ catalytically formed by fusion-expressed peroxidases are visible under XRM. Using this new tag, we imaged the protein location associated with the alteration of a DNA-methylation pathway with an ultra-high resolution of 30 nanometers. Importantly, the excellent energy resolution of XRM enables multicolor imaging using different peroxidase tags. The development of GXET enlightens the way to nanoscopic imaging for biological studies.     

关节软骨胎龄形态学光镜观察

关节软骨损伤难以修复，过去的研究多集中于动物和成人，很少对胎儿关节软骨进行研究。对头臀长146—280mm胎儿的股骨髁关节软管最表层结构、继续生长方式、营养与代谢等方面进行了光镜观察。     

单分子操纵与调控

由于具备在空间和能量尺度的高分辨表征能力以及纳米局域探针特点,扫描隧道显微术已经成为近年来对单分子体系进行空间、结构操纵和物理、化学性质调控的重要工具。它可以操纵单分子及其组元在材料表面进行各种运动模式乃至化学反应,并通过电致等外场效应调节单分子体系的量子态,从而在新型材料探索、纳米器件设计、化学反应机理研究与控制等领域具有极大的应用潜力。     

Mineralogical and microstructural characteristics of historic Roman cement renders from Budapest,Hungary

Roman cements, one of the most extensively produced types of hydraulic binders of the second half of the 19th century, played an important role in the architecture of many European countries. This paper deals with the chemical-mineralogical and microstructural characterisation of historic Roman cement renders from Budapest, Hungary. Different microscopic techniques were used on polished thin sections and fracture surfaces in order to understand the method of producing these renders and the effect of urban pollution on them. The renders exhibited characteristics typical to a Roman cement mortar, such as high binder to aggregate ratios (b/a), mostly fine-grained aggregates and high capillary porosity, but without the shrinkage cracks that are also normally present. This research suggests that coarse residual cement grains may have acted in a manner similar to aggregates by absorbing stress and thereby reducing the formation of shrinkage cracks. Based on the mineral characteristics of residual cement grains, the samples could be divided into two groups, which correspond to either a higher or lower temperature of calcination of the original source material of the cement. Chemical characteristics of the binders suggest the presence of intermixed CaCO₃ originating from the carbonation of hydration products and partly from residual calcium carbonate of the raw material. Despite dense and often impermeable coats applied in later renovations and exposure to a polluted urban environment, which resulted in formation of gypsum on the surface of the renders, the samples show good to excellent state of preservation after more than a century. The strong “house of cards”-like arrangement of the complex C-(A)-S-H-type phases is responsible for both the high capillary porosity and the good resistance of Roman cement renders to atmospheric pollution and potentially damaging salts such as Na- and K-chlorides which are found near the base of the building due to sidewalk de-icing. These results help to better understand the behaviour of historic Roman cement renders, which in turn assists in making good decisions in choosing a repair material to future restorations of 19th century façades built with this material.     

铁磁-量子点-超导体异质结中的自旋电导

分析铁磁-量子点-超导体异质结中,量子点内存在自旋翻转相互作用时的自旋输运问题. 采用非平衡格林函数方法,计算隧穿自旋流和自旋电导. 结果表明,即使在一般温度和自旋极化强度下,自旋电导依赖于铁磁体内交换场方向,产生可控的巨自旋磁阻效应.     

嵌入式设备多存储介质媒体库统一查询方法

智能手机、带存储介质的嵌入式设备,一般会存储大量的图片、音乐、视频等多媒体文件。只有少部分媒体播放器带有文件的搜索和管理功能,但是功能有限,操作也不统一。首先对磁盘文件目录作递归扫描,根据文件名后缀作过滤和分类,用嵌入式数据库sqlite3来存储扫描结果;然后介绍了分类查询、文件名汉字拼音首字母查询、即输即查的快速模糊查询技术,还特别对多分区和多介质的情况作了处理,支持多介质的统一查询。此方法可用来轻易构建软件,给智能手机或其它嵌入式设备用户一种全方位的媒体库管理体验。     

The Effects of Artificial Incomplete Burning on the Morphology and Dimensions of Cellulosic and Proteinaceous Textiles and Fibres

ABSTRACT

The aim of this research was to produce reference data for the study and identification of fibres of carbonised excavated textiles. Thus, the effects of carbonisation (incomplete burning) on the morphology and dimensions of selected fibres used in textile production were investigated. A set of standard test, commercial, and hand-made fabrics, of four cellulosic (cotton, flax, hemp, nettle) and two proteinaceous (silk, wool/ wool felt) fibres, were used for the experiments. Samples were carbonised in a limited oxygen environment at 250, 350, and 500°C for one hour (apart from the wool samples for which the duration of the experiment had to be lowered to six minutes). Wool and silk samples were destroyed at temperatures above 250°C. All cellulosic and the silk samples shrank and their weight was reduced at different percentages that increased as the temperature increased. Exceptionally, wool textile samples exhibited extreme shrinkage but also an increase in their weight. Similarly, the fibre diameters of the cellulosic and silk fibres shrunk gradually at different degrees as the temperature increased, and some exhibited marked degradation patterns, like lacerations in flax, ridges in hemp, raggedness in nettle, and cracks in silk fibres. Wool fibres swell locally but retained the scale pattern on the surface. In general, an increase in the weave count of the textile samples was observed. However, the morphology of the fibres characteristic to their identification did not alter to an unrecognisable degree as a result of artificial carbonisation, as long as the material was preserved.     

针刺和静力牵张对大负荷运动后骨骼肌收缩结构变化影响的免疫电镜研究

用免疫电镜的方法观察大负荷运动后骨骼肌收缩结构变化时M蛋白、α-辅肌动蛋白和肌球蛋白的定位,以探索超过习惯负荷后收缩结构延迟性变化的性质,以及针刺和静力牵张对促进其恢复的机理,结果发现:在多组力竭性工作后,收缩结构发生变化的同时,伴有该结构的免疫标记密度下降以及有关收缩蛋白的免疫标记向其结构以外区域扩散,这一结果提示:超过习惯负荷后收缩结构变化或解体是由于延迟性的收缩蛋白的降解优势所致。由于这种变化是一过性的,经过休息和调整训练负荷即可能恢复,并未形成稳定的改变,因而其性质仍可认为是生理性的或是生理向病理性变化的过渡状态。针刺和静力牵张能通过加强收缩蛋白的合成代谢而有效地促进收缩结构的恢复并出现疼痛的消除,其作用的机理尚待进一步的研究。     

不同运动强度大鼠心肌间质胶原网络结构重塑的扫描电镜观察

在不同运动强度实验动物模型上,采用扫描电子显微镜对心肌间质胶原网络结构重塑进行了观察研究。结果显示,心肌间质胶原网络结构在心肌、毛细血管及心内膜间以4种方式广泛分布,即“框格式”联接,“树根样”联接,直接联接和细胞内联接。运动可引起心肌间质胶原网络结构的重塑,一般运动负荷可使心肌与间质胶原网络同步增长,以适应心肌细胞肥大收缩力增加从而保证肌束间及心肌细胞间力的传递;运动超负荷可使心肌束间、心肌细胞间以及小动脉和毛细血管间不同类型胶原大量蓄积增生,导致心脏的僵硬度增加,舒缩功能降低。