Students as Virtual Scientists: An exploration of students' and teachers' perceived realness of a remote electron microscopy investigation     

Gina Childers  M. Gail Jones 《International Journal of Science Education》2013,35(15):2433-2452

Remote access technologies enable students to investigate science by utilizing scientific tools and communicating in real-time with scientists and researchers with only a computer and an Internet connection. Very little is known about student perceptions of how real remote investigations are and how immersed the students are in the experience. This study, conducted with high school students and their teachers, explored the impact of students' perception of ownership and virtual presence during a remote investigation using a scanning electron microscope. Students were randomly assigned to one of two treatment groups: students able to select their own insect to use during the remote investigation, and students that did not select their own insects to view during the remote investigation. The results of this study showed that students in the experimental group who had choice and ownership of their insect reported being more present (less distracted) during the remote investigation than students in the control group, whereas students in the control group reported controlling the technology was easier than the experimental group. Students indicated the remote investigation was very real; however, the teachers of these students were less likely to describe the investigation as being real. The results of this study have practical implications for designing remote learning environments.  相似文献   

Genetically encoded X-ray cellular imaging for nanoscale protein localization     

Huating Kong  Jichao Zhang  Jiang Li  Jian Wang  Hyun-Joon Shin  Renzhong Tai  Qinglong Yan  Kai Xia  Jun Hu  Lihua Wang  Ying Zhu  Chunhai Fan 《国家科学评论(英文版)》2020,7(7):1218

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.  相似文献   

关节软骨胎龄形态学光镜观察     

王春阳  宋君毅  胡声宇 《武汉体育学院学报》2003,37(3):43-45

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。  相似文献   

单分子操纵与调控          下载免费PDF全文

侯建国 《中国科学院院刊》2011,(Z1):46-51

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。  相似文献   

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

《Journal of Cultural Heritage》2014,15(3):219-226

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.  相似文献   

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

Christina Margariti 《文物保护研究》2020,65(7):388-398

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.  相似文献   

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   总被引：2，自引：0，他引：2  

卢鼎厚  樊景禹  屈竹青  李晓楠 《体育科学》1992,(6)

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。  相似文献   

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   总被引：15，自引：0，他引：15  

田振军 《体育科学》1999,19(3):70-73

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。  相似文献   

四味润肺中药对小鼠被动吸烟的保护作用     

余书勤  单世明 《科技通报》1995,11(5):324-328

应用耐缺氧试验、光镜及扫描电镜等方法探讨了四味润肺中药对小鼠被动吸烟的保护作用．结果表明，被动吸烟可导致小鼠耐缺氧时间缩短，气管内膜上皮可见光镜及扫描电镜下病理性改变．太子参及川贝对吸烟所致损害的保护作用较强，玉竹的作用较差．  相似文献   

国家级创新性高端科学研究基础平台建设——高水平的科学研究带动高质量的开放服务     

朱静 《实验技术与管理》2011,28(1)

阐述建立国家科技基础条件平台——国家大型科学仪器中心的重要意义,介绍北京电子显微镜中心建设的情况和所取得的部分科研成果。北京电子显微镜中心是在清华大学原电子显微镜实验室的基础上建立起来的,通过实践高水平的科学研究带动高质量的开放服务的管理理念,建立并执行科学的管理规章制度,不断创新运行机制和改进工作,使中心不断发展和壮大。  相似文献