Essential oil composition and antimicrobial activity of Sphallerocarpus gracilis seeds against selected food-related bacteria

Sphallerocarpus gracilis from China is a little-investigated edible and medicinal plant. In the present study, the essential oil composition from S. gracilis seeds was investigated by GC and GC–MS. A total of 34 compounds representing 94.69% of the essential oil were tentatively identified. The main constituents were p-cymene (17.42%), γ-terpinene (25.58%) and α-asarone (33.12%). The antimicrobial activity, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of the essential oil from S. gracilis seeds were evaluated against eight Gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Bacillus megaterium, Bacillus cereus, Bacillus coagulans and Bacillus subtilis), four Gram-negative bacteria (Salmonella enteritidis, Salmonella typhimurium, Klebsiella pneumoniae and Escherichia coli) and one fungus (Aspergillus niger). Results revealed that the essential oil from S. gracilis seeds exhibited significant in vitro antimicrobial property. Among all the tested microorganisms, the essential oil showed the strongest inhibitory effect against K. pneumoniae, whereas no inhibitory effect was found against L. monocytogenes and A. niger. Additionally, scanning electron microscopy (SEM) was used to observe morphological changes of bacteria treated with the essential oil from S. gracilis seeds. SEM observations confirmed the physical damage and considerable morphological alteration to the tested microorganisms treated with the essential oil. The data of this study suggests that the essential oil from S. gracilis seeds has great potential for application as a natural antimicrobial agent to preserve food.     

Improve on/off ratio of organic heterojunction transistors by adopting single-sandwich configuration

Organic heterojunction transistors (OHJTs) based on 5,5′″-bis(naphtha-2-yl)-2,2′:5″,2′″-quaterthiophene (NaT₄)/copper-hexadecafluoro-phthalocyanine (F₁₆CuPc) heterojunction were fabricated in single-sandwich and sandwich configurations, respectively. All the devices operated in depletion-accumulation (normally-on) mode. High field-effect mobility of 0.35 cm²/Vs was obtained for all devices, which was higher than that, 0.20 cm²/Vs of the devices with NaT₄ as active layer. The on/off ratio of 1 × 10⁵ was obtained for OHJTs with single-sandwich configuration, which is three orders of magnitude higher than that of OHJTs with sandwich configuration. Compared with OHJTs with sandwich configuration, the higher on/off ratio was mainly determined by the lower off state current in OHJTs with single-sandwich configuration. In OHJTs with single-sandwich configuration, the well-type shield effect of the source and drain electrodes caused a very narrow empty region in F₁₆CuPc film, which is responsible for the lower off state current.     

Study on Thermal Deformation Behavior and Properties of Vacuum Hot-press Sintered W(50)/Cu-Al_2O_3 Composite

In this work, the tungsten particulate reinforced Al2O3 dispersion strengthened copper base composites were successfully fabricated by using a vacuum hot-press sintering method. With the test temperature varying from 650 to 950 ℃ and the strain rate varying from 0.01 to 5 s-1, the W(50)/Cu-Al2O3 composites were isothermally compressed on a Gleeble-1500D thermal simulator. The true stress-strain curves of the W(50)/Cu-Al2O3 under different test conditions were obtained. The dynamic recrystallization of the W...     

Reliability-based bond design for GFRP-reinforced concrete

Most of proposed models available so far associated with the evaluation of design embedded length of fiber reinforced polymer (FRP) rods in concrete are not reliability-based. This paper made an attempt, from the probabilistic standpoint, to determine the design embedded length of a glass fiber reinforced polymer (GFRP) rod in the case of splitting bond failure from concrete. The mathematical model put forward by Orangun et al. for evaluating the average bond strength of reinforcing bars in concrete for splitting failure has been adopted to develop the nonlinear limit state function corresponding to GFRP’s splitting bond failure in which five independent random variables, i.e. concrete strength, GFRP tensile strength, embedded length, GFRP diameter and computational uncertainty factor, are included. As the result of the probabilistic calibration procedures using the Rackwitz–Fiessler method, a non-dimensional factor K associated closely with the design embedded length of a GFRP rod in concrete is proposed to be 0.0306 with the suggested additional target reliability index of 1.10. The effects of some factors on GFRP’s design embedded length have been identified through the following parametric study. Although the calibration process is case-dependent to some extent, the proposed formula is thought to be acceptable for general bond design purposes of GFRP-reinforced concrete components.     

硅烷改性聚合物密封剂的研究进展

详细阐述了硅烷改性预聚体的合成方法和硅烷改性聚合物密封剂的制备及固化机理,总结了国内外硅烷改性聚合物密封剂的研究现状及进展,最后分析了硅烷改性聚合物密封剂在我国工业发展中的重要作用。     

快速注浆法在立井井筒水害治理中的应用

介绍了在井筒施工中采用快速注浆法封堵基岩段裂隙水主要涌水通道的方法。     

浅析标准厂房的开发与设计

改革开放以来,中国的经济社会发展突飞猛进,中小企业在市场中寻找到商机之后,需要在最短的时间内以投资最省的方式使产品批量生产,投放市场,以在市场的竞争中立于不败之地。基于此,标准厂房的诞生有了它的市场基础。20世纪80年代末期,全国掀起了工业园区开发的第一次浪潮,标准厂房的建设和土地批租一起成为工业区招商引资的重要手段。文章基于作者多年从事标准厂房设计的工作经验,介绍标准厂房的一种开发设计思路,供同行参考借鉴。     

台湾地区容积转移制度解析

容积转移是一项用于平衡市场开发与空间资源保护的弹性调控技术。本文在介绍台湾容积转移制度利益属性基础上,分析了容积转移的构成要素、实施框架与运作机制,并从中解析台湾地区实践的经验与风险,旨在健全我国大陆地区现行的容积率控制体系。     

基于D-FNN的发电机转子匝间故障诊断

针对目前智能方法在汽轮发电机转子匝间短路故障诊断中存在的不足,提出了一种基于扩展径向基（RBF）神经网络的动态模糊神经网络D-FNN的智能诊断方法。与传统的BP神经网络不同,D-FNN的结构不是预先设定而是在训练中实时动态产生并修剪,从而使该方法能有效避免BP神经网络结构确定不合理,容易陷入局部最小,收敛速度慢,精确度不高等缺点。通过在Matlab/Simulink下仿真一台发电机并网运行时转子绕组匝间短路故障获取训练样本。使用训练好的D-FNN进行故障诊断,诊断结果表明了该方法的有效性、实用性和优越性,达到了预期诊断目的。     

电机转子断条故障诊断方法探讨

通过综合国内外相关理论,对笼型异步电动机几种转子断条故障诊断方法进行了研究.仿真或实验验证结果表明,所有的方法对检测笼型异步电动机的转子故障是有效的.在此基础上讨论了转子断条故障诊断方法的发展趋势,为电机转子断条故障研究者提供了理论指导.