Surface disposition and stability of pest-interactive,trichome-exuded diterpenes and sucrose esters of tobacco

The precise physical location of trichome-exudate biochemicals on the plant surface is undoubtedly important in plant-pest interactions, perhaps particularly those involving fungal and bacterial pathogens that invade the plant through the epidermal layer. The chemical stability of exuded compounds is also important in this regard. Here we have studied these two aspects of trichome biology using the highly exuded tobacco line,Nicotiana tabacum, T.I. 1068. Particularly under high relative humidity growth conditions, sucrose esters (SE) were found to migrate from the exudate droplet around the gland down the trichome stalk to the epidermal cells below. Six days after labeling leaf midveins on plants grown in a high humidity environment, 29 and 71% of label found in SE were recovered with trichome glands and below gland regions, respectively. Corresponding disposition in the moderate humidity environment was 40 and 60%, respectively. Migration of less polar duvatrienediols (DVT) was less marked. Staining of SE with rhodamine B showed the occurrence of more extensive and physically different migration in the high humidity versus moderate humidity case. Both SE and DVT were stable between six and 18 days postlabeling, the period encompassing the time of maximum exudate formation through the beginning of tissue senescence. Our results suggest that even under conditions that avoid mechanical disturbance of tissue, SE and DVT are chemically stable, at least until senescence, and appear to migrate from the gland region to the epidermal surface, apparently according to their relative polarity.     

统计分析技术在焊接培训中的应用

在传统焊接培训过程中,因培训数据量较大,人工无法从这些数据信息中来评价教与学的质量。文中使用描述性分析和推断分析项结合的方法来对培训记录进行分析、统计,从培训教与学的记录出发,分析培训周期长的根源,能够对焊接水平做监控指导,可以作为综合评估教师教授和学员学习情况的有效手段之一,对教师的教学水平和学员的学习能力以及适应学习的能力做综合掌握和控制,能在一定程度上指导教与学的工作,从而有针对性地进行培训,缩短培训周期,提高工作效率。     

水煤浆添加剂及水煤浆稳定性的研究

研究了实验室中制备水煤浆的方法,选择了合适的煤种和适合成浆的煤粉粒度分布。使用了不同分子结构的高分子阴离子型表面活性剂作为添加剂制备水煤浆。研究了不同分子结构的添加剂对同种煤质的水煤浆成浆性的性能比较,选择出了合适的主添加剂。探讨了添加剂的添加量与煤的成浆性、流变性以及静态稳定性的关系。结果表明,添加剂的分子链长短、分子链上的活性基团的多少等因素以及在煤浆中的添加量对水煤浆的成浆性、黏度、质量分数、流变性以及稳定性具有显著的影响。     

提高次氯酸钠溶液稳定性

通过次氯酸钠溶液有效氯含量的测定，对次氯酸钠溶液的稳定性进行了初步分析探讨，提出了一些应对措施。     

水计量系统数据传输稳定性的提高

针对莱钢水计量系统数据传输不稳定的问题,提出改变传输方式、加装LGF智能流量仪、利于GPRS无线通信技术、实现远程网络连接、加装网络通信系统的信号防雷保护等改造措施。     

Temporal evolution of contacts and communities in networks of face-to-face human interactions

Temporal dynamics of social interaction networks as well as the analysis of communities are key aspects to gain a better understanding of the involved processes, important influence factors, their effects, and their structural implications. In this article, we analyze temporal dynamics of contacts and the evolution of communities in networks of face-to-face proximity. As our application context, we consider four scientific coil- ferences. On a structural level, we focus on static and dynamic properties of the contact graphs. Also, we analyze the resulting community structure using state-of-the-art automatic community detection algorithms. Specifically, we analyze tile evolution of contacts and communities over time to consider the stability of the respective conmmnities. Furthermore, we assess different factors which have an influence on the quality of com- munity prediction. Overall, we provide first important insights into the evolution of contacts and communities in face-to-face contact networks.     

网络安全事件关联分析与态势评测技术研究

随着网络应用的普及,网络涉及的范围越来越广,网络安全是网络应用中的重要课题。文章对网络中发生的安全事件进行分析,介绍了从传导路径的角度和事件关联关系的角度对安全事件进行分析的方法,并建立网络安全事件势态评测模型,从网络环境的角度和事件自身属性的角度诠释网络安全事件态势。     

Towards evolvable Internet architecture-design constraints and models analysis

There is a general consensus about the success of Internet architecture in academia and industry. However, with the development of diversified application, the existing Internet architecture is facing more and more challenges in scalability, security, mobility and performance. A novel evolvable Internet architecture framework is proposed in this paper to meet the continuous changing application requirements. The basic idea of evolvability is relaxing the constraints that limit the development of the architecture while adhering to the core design principles of the Internet. Three important design constraints used to ensure the construction of the evolvable architecture, including the evolvability constraint, the economic adaptability constraint and the manageability constraint, are comprehensively described. We consider that the evolvable architecture can be developed from the network layer under these design constraints. What＇s more, we believe that the address system is the foundation of the Internet. Therefore, we propose a general address platform which provides a more open and efficient network environment for the research and development of the evolvable architecture.     

改性水泥专用丁苯胶乳的稳定性研究

以十二烷基苯磺酸钠为乳化剂,用过硫酸钾引发体系,制备了改性水泥专用丁苯胶乳,考察了乳化剂浓度、进料方式和搅拌形式对胶乳稳定性的影响.     

Thermogravimetric analysis of methyl methacrylate‐graft‐natural rubber

The thermal degradations of methyl methacrylate‐graft‐natural rubber (MG) at different heating rates (B) in nitrogen were studied by thermogravimetric analysis. The results indicate that the thermal degradation of MG in nitrogen is a one‐step reaction. The degradation temperatures increase along with the increment of heating rates. The temperature of initial degradation (T₀) is 0.448B + 362.4°C, the temperature at maximum degradation rate, that is, the peak temperature on a differential thermogravimetric curve (T_p) is 0.545B + 380.7°C, and the temperature of final degradation (T_f) is 0.476B + 409.4°C. The degradation rate at T_p is not affected by B, and its average value is 48.9%; the degradation rate at T_f is not affected by B either, and its average value is 99.3%. The reaction order (n) is 2.1 and is not affected by B. The reaction activation energy (E) and the frequency factor (A) increase along with B, and the apparent reaction activation energy (E₀) is 254.6 kJ/mol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2952–2955, 2002