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51.
Rudolf H. Scheffrahn Ruei-Ching Hsu Nan-Yao Su Jacob B. Huffman Sharon L. Midland James J. Sims 《Journal of chemical ecology》1988,14(3):765-776
The heartwood of bald cypress,Taxodium distichum (L.) Rich., resisted feeding attack by the Formosan subterranean termite,Coptotermes formosanus Shiraki. Hexane-extracted heartwood, however, was consumed at > 12 times the amount of sound heartwood eaten. A bioassay usingT. distichum sapwood as a feeding substrate was employed to assess the antitermitic activity of successive hexane, acetone, and methanol extracts of heartwood shavings and isolates derived from the active hexane extract. Two fractions, eluted from the crude hexane extract by liquid chromatography, significantly reduced termite feeding compared to the parent extract, while a third fraction was less active than the original hexane extract. Each fraction contained one major component. All three components were structurally related diterpenes. The two most active heartwood constituents were identified by GC-MS and NMR as ferruginol and manool, while the third and least active, but most prevalent, compound in heartwood was identified as nezukol. Results of bioassays suggest that these allelochemicals act principally as feeding deterrents with accompanying termite mortality due to starvation. 相似文献
52.
A positive‐working, aqueous‐base‐developable photosensitive polyimide precursor based on poly(amic ester)‐bearing phenolic hydroxyl groups and a diazonaphthoquinone photosensitive compound was developed. The poly(amic ester) was prepared from a direct polymerization of 2,2′‐bis‐(3‐amino‐4‐hydroxyphenyl)hexafluoropropane and bis(n‐butyl)ester of pyromellitic acid in the presence of phenylphosphonic dichloride as an activator. Subsequently, the thermal imidization of the poly(amic ester) precursor at 300°C produced the corresponding polyimide. The inherent viscosity of the precursor polymer was 0.23 dL/g. The cyclized polyimide showed a glass‐transition temperature at 356°C and a 5% weight loss at 474°C in nitrogen. The structures of the precursor polymer and the fully cyclized polymer were characterized by Fourier transform infrared spectroscopy and 1H‐NMR. The photosensitive polyimide precursor containing 25 wt % diazonaphthoquinone photoactive compound showed a sensitivity of 150 mJ/cm2 and a contrast of 1.65 in a 3 μm film with 1.25 wt % tetramethylammonium hydroxide developer. A pattern with a resolution of 10 μm was obtained from this composition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 352–358, 2002 相似文献
53.
SiC coatings on the surface of C-C were produced by either silicone resin impregnation/ pyrolysis or reaction sintering. Cycles of resin impregnation/pyrolysis produced an SiC coating, on the walls of fine open pores, which was effective in reducing the oxidation rate of C-C and in shifting the transition temperature to a higher value. Unless it is pre-coated with a pyrocarbon layer before sintering, plain reaction sintered SiC has oxidation behaviors similar to those of the above-mentioned SiC. The dense pyrocarbon film deposition on the surface of C-C could form a better SiC film than others. The carbon film homogenized the surface of C-C and a dense SiC film was established. The oxidation of the coated C-C can be modelled by a set of “oxidation resistors” in series and/or in parallel, with each resistor corresponding to an oxidation element. The controlling mechanism can be resolved from the activation energy. A combined resistant layer, consisting of resin impregnation, pyrocarbon film and reaction sintering SiC, showed the best oxidation resistance of any single-layer coated C-C composite. 相似文献
54.
马氏体相变研究的进展和瞻望SCIEI 总被引:1,自引:0,他引:1
叙述马氏体相变研究的一些进展和瞻望,包括马氏体相变的定义,马氏体相变热力学,奥氏体状态对马氏体相变的影响,动力学,形核和长大,以及马氏体相变晶体学。 相似文献
55.
Michael J. McNallan Ph.D. Pei Pei Hsu Ph.D. Soo Young Lee Ph.D. 《JOM Journal of the Minerals, Metals and Materials Society》1993,45(12):22-25
Nonoxide silicon-based ceramics owe their oxidation resistance to the formation of a thin silica film that separates the ceramic from oxidizing environments. This silica film can be fluxed by alkali oxides to form low-melting alkali silicate corrosion products that do not provide protection. Alkali chlorides and other halides have sufficiently high vapor pressures that silica fluxing can occur without the formation of a condensed halide salt. The rates of oxidation of Si, SiC, and Si3N4 are influenced by the composition of gas mixtures containing these species. 相似文献
56.
Hualong Li Emilie Hsu Jerzy Szpunar Ravi Verma Jon. T. Carter 《Journal of Materials Engineering and Performance》2007,16(3):321-326
In order to determine the deformation modes in AZ31 magnesium alloy at room temperature, computer simulations of deformation
texture development and calculation of formability have been carried out. The simulation results were compared with the measured
texture results. Based on agreement between the experiments and simulations the active deformation modes were determined.
A Visco Plastic Self Consistent model was employed for the simulation of plastic deformation. Simulations and experiments
were performed for different initial textures. The goal of the study was to develop the understanding of deformation texture
evolution and its effects on mechanical properties of magnesium, with an ultimate goal of improving room temperature formability
of magnesium alloys.
This article was presented at Materials Science & Technology 2006, Innovations in Metal Forming symposium held in Cincinnati,
OH, October 15-19, 2006. 相似文献
57.
Ao Zhou Shangguang Wang Ching-Hsien Hsu Qibo Sun Fangchun Yang 《Multimedia Tools and Applications》2016,75(20):12901-12917
An increasing number of big-data services are being deployed in a cloud computing environment, attracted by the on-demand service, rapid elasticity, and low maintenance costs. As a result, ensuring the quality of service has become an important research problem. Traditionally, task rescheduling is used to ensure a consistent quality of service in the event of failure of a virtual machine. However, the network resource consumption of different rescheduling methods varies. To address this problem, we propose a task rescheduling method that minimizes network resource consumption.The method includes three algorithms. The first obtains a set of good virtual machines from the large quantity of service-providing virtual machines using the skyline operation. A ranking algorithm then fuses the data size and the task emergency to identify significant tasks. Finally, we present an algorithm that automatically determines the optimal insertion point for each task. To verify the effectiveness of the proposed method, we extend the renowned simulator CloudSim and conduct a series of experiments. The results show that our method is more efficient than other methods in terms of network resource consumption. 相似文献
58.
Boris Hudec Chung-Wei Hsu I-Ting Wang Wei-Li Lai Che-Chia Chang Taifang Wang Karol Fröhlich Chia-Hua Ho Chen-Hsi Lin Tuo-Hung Hou 《中国科学:信息科学(英文版)》2016,59(6):061403
In this article, we comprehensively review recent progress in the ReRAM cell technology for 3D integration focusing on a material/device level. First we briefly mention pioneering work on high-density crossbar ReRAM arrays which paved the way to 3D integration. We discuss the two main proposed 3D integration schemes—3D horizontally stacked ReRAM vs 3D Vertical ReRAM and their respective advantages and disadvantages. We follow with the detailed memory cell design on important work in both areas, utilizing either filamentary or interface-limited switching mechanisms. We also discuss our own contributions on HfO2-based filamentary 3D Vertical ReRAM as well as TaOx/TiO2 bilayer-based self-rectifying 3D Vertical ReRAM. Finally, we summarize the present status and provide an outlook for the nearterm future. 相似文献
59.
Dong-Her Shih Sheng-Fei Hsu Chia-Chia Lin 《International journal of human-computer interaction》2013,29(10):627-645
Even though the ubiquity of technology can make many aspects of life more convenient, it may simultaneously raise some concerns about the privacy issues related to personal information. This research focused on the individual's behavior toward self-disclosure online and his or her cognition on personal privacy that was affected by not only the personal psychological factors but also the individual's computer knowledge and associated skills. To study how technological and psychological factors can simultaneously affect one's privacy concern and restrain behavior on disclosure, this study applied both perceived privacy and privacy concern to assess such factors as personal subjective attitude, computer self-efficacy, and perceived behavioral control to investigate the technological influence. A hypothesized model was proposed to describe the relationships among these constructs. After structural equation modeling is utilized to analyze the proposed hypotheses, the research findings showed that, although the perceived behavioral control had a negative effect on self-disclosure online, all the other hypotheses indicated a positive casual effect. 相似文献
60.
Kuo‐Chung Huang Yi‐Heng Chou Lang‐chin Lin Hoang Yan Lin Fu‐Hao Chen Ching‐Chiu Liao Yi‐Han Chen Kuen Lee Wan‐Hsuan Hsu 《Journal of the Society for Information Display》2013,21(6):263-270
The optimal viewing distance was proposed as a parameter for designing a parallax barrier 3D display. It can be designed based on simple geometric method and by considering the pitches of image display pixels and parallax barrier, or even including the aperture ratios of the image display pixels and parallax barrier. It can be analyzed by using ray tracing method. By considering the optical refraction index of the cover glass, the angular behavior of the system becomes more realistic; however, the geometric method is difficult to be used. We propose a revised method for estimating the view distance and angular behavior. In this paper, we have demonstrated a designated eye position (DEP) for each view and shown that multiple DEPs make a circular curve around the center of the display. We prove the new concept by comparing the optical ray tracing calculations and optical measurement. 相似文献