环氧季铵盐对明胶的阳离子化改性

碱性条件下,环氧季铵盐1,2-环氧丙基二甲基十二烷基氯化铵(EPQA)与明胶侧链的伯胺基、羟基反应,得到阳离子改性明胶EPQA-GE,核磁共振(~(13)C-NMR、~1H-NMR)及元素分析结果表明,精氨酸、赖氨酸的氨基以及羟脯氨酸的羟基参与了反应,季铵阳离子基团成功引入了明胶结构中。X射线衍射及差示扫描量热分析结果表明,明胶的微观相结构受阳离子含量的影响较大,引入的季铵离子越多,EPQA-GE的近程有序度越高。以水和乙二醇为标准液,测定了阳离子化程度不同的EPQA-GE膜的接触角,并应用Owens-Wendt方程计算了表面自由能,结果显示阳离子基团的引入增加了明胶的亲水性,且随着阳离子化程度增加,膜表面的亲水性增强。抗菌实验结果表明阳离子的引入增加了明胶的抗菌性,EPQA-GE对革兰氏阳性菌的抗菌效果优于对革兰氏阴性菌的抗菌性。     

用于烯烃复分解反应的钌茚基催化剂的合成研究进展

基于钌金属的烯烃复分解反应现今已成为一种至关重要且快速有效的催化反应类型,在聚合领域以及现代有机合成的应用方面起着改革性的推进作用。作为烯烃复分解反应催化剂的一种,钌茚基催化剂在该领域得到成功应用。结合近年来钌茚基催化剂在烯烃复分解反应中的合成研究进展,简述了其发展过程,介绍了该领域创新性的研究成果,重点论述了一些新型钌茚基催化剂的合成方法,并且探讨了辅助配体的结构对催化剂稳定性和活性的影响,最后对其发展方向以及应用前景进行了展望。     

不同形貌α-Fe2O3的水热法制备及性能研究

以Fe(NO_3)_3·9H_2O为原料,聚乙烯吡咯烷酮作为表面活性剂,NaOH、Na_2CO_3、CH_3COONa为形貌改变剂,采用水热法制备出不同形貌的α-Fe_2O_3,并研究了不同因素对产物形貌的影响。利用SEM、EDS、XRD、FTIR等手段对其物相及微观形貌进行表征,并探讨其生长机理。通过光催化降解酸性大红模拟废水考察不同形貌α-Fe_2O_3的光催化性能,实验结果表明,类桑葚状α-Fe_2O_3对酸性大红模拟废水的降解效果最好,降解率高达99.01%,具有潜在的光催化应用前景。     

Unpowered Knee Exoskeleton Reduces Quadriceps Activity during Cycling

Cycling is an eco-friendly method of transport and recreation. With the intent of reducing the energy cost of cycling without providing an additional energy source, we have proposed the use of a torsion spring for knee-extension support. We developed an exoskeleton prototype using a crossing four-bar mechanism as a knee joint with an embedded torsion spring. This study evaluates the passive knee exoskeleton using constant-power cycling tests performed by eight healthy male participants. We recorded the surface electromyography over the rectus femoris muscles of both legs, while the participants cycled at 200 and 225 W on a trainer with the developed wheel-accelerating system. We then analyzed these data in time–frequency via a continuous wavelet transform. At the same cycling speed and leg cadence, the median power spectral frequency of the electromyography increases with cycling load. At the same cycling load, the median power spectral frequency decreases when cycling with the exoskeleton. Quadriceps activity can be relieved despite the exoskeleton consuming no electrical energy and not delivering net-positive mechanical work. This fundamental can be applied to the further development of wearable devices for cycling assistance.     

Towards the appropriate human-centred information systems: A case study of the Japanese retail industry

The industries of Japan have developed by learning from Western industries, especially the USA, and by implementing many of their concepts and technologies. However, Japanese industries have often implemented these concepts and technologies in a very different way from the USA. For example, while the USA uses information systems in retail industries as a tool by which data are collected and analysed to control the market, in Japan this same technology is considered rather as a learning device to interpret the market. While in the USA the market is seen as a natural phenomenon capable of being controlled, the Japanese see it as an ambiguous phenomenon that is ever changing and is not capable of being controlled. Rather it is important to feel the change in the market itself.This paper introduces human centredness to the information system, and argues against modern rationalism, i.e. human versus technology, taking the case of use of POS data from the POS system (point of sale: a system that collects data on both the customer and goods sold by scanning bar codes that are attached to the surface of the goods) by the eminent Japanese retailer, Ito-Yokado. It emphasises an interactive concept of interaction between human and technology of the postmodern paradigm.     

煤与瓦斯突出联网系统的应用研究

介绍了煤与瓦斯突出联网系统的总体结构和联网数据的形成。该系统通过分析和计算各矿井的煤质结构、地压活动范围和瓦斯倍率的密切关系,得出判断煤与瓦斯突出事故的综合分析指标,以预测与防治事故的发生。实际应用表明,该系统实现了对煤与瓦斯突出的预测功能。     

以任务为中心的LAMS学习活动设计

以网络教学平台的LAMS(学习活动管理系统)为依托,以"Photoshop图像处理"课程中的实际应用为例,阐述在网络辅助教学中,在以任务为导向的学习活动设计和应用中遇到的问题,及其对学生的学习兴趣和学习效果的影响,并提出LAMS改进方向。     

Analysis of multi-agent activity using petri nets

This paper presents the use of place/transition petri nets (PNs) for the recognition and evaluation of complex multi-agent activities. The PNs were built automatically from the activity templates that are routinely used by experts to encode domain-specific knowledge. The PNs were built in such a way that they encoded the complex temporal relations between the individual activity actions. We extended the original PN formalism to handle the propagation of evidence using net tokens. The evaluation of the spatial and temporal properties of the actions was carried out using trajectory-based action detectors and probabilistic models of the action durations. The presented approach was evaluated using several examples of real basketball activities. The obtained experimental results suggest that this approach can be used to determine the type of activity that a team has performed as well as the stage at which the activity ended.     

基于DSP的矿井光纤直放系统的设计

根据煤矿井下巷道狭长、拐点多、分支多的特点,针对井下环境中移动通信系统通话质量差、可靠性低等问题,提出了一种基于DSP的矿井光纤直放系统的设计方案,详细介绍了系统基于DSP的自动监控单元和FIR数字滤波器的设计及语音激活技术在直放系统中的应用。该光纤直放系统解决了井下广域范围移动通信问题,采用DSP对系统实施自动监控,为系统稳定运行提供了可靠保障;数字滤波器的引入、话音激活技术的应用使井下通信系统性能更稳定、话音质量更好、抗干扰性更强,为矿井移动通信的最佳实现奠定基础。     

有效地设计创意点

设计是创意产业,同时也是理性的、有据可循的。通过特定的方式寻找设计的创意点,有助于设计师诞生更多的优秀的设计作品。本文通过使用者的行为分析、多功能产品、特殊人群、情感化设计等方面,结合具体的设计案例,分析这些优秀设计创意点的产生,总结出寻找有效设计创意点的方法。