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71.
Nanofiber bundles of Ag2S, Ag2Se, and Ag have been successfully synthesized by making use of Ag2C2O4 template nanofiber bundles, utilizing both anion‐exchange and redox reactions. The obtained bundles were polycrystalline nanofibers composed of nanoparticles in which the precursor morphology was well‐preserved, indicating that Ag2C2O4 nanofiber bundles acted as a general sacrificial template for the synthesis of silver‐based semiconductor and metal nanofibers. Dispersing media and transforming reactants were found to be key factors influencing the chemical transformation in the system. In particular, separate single‐crystalline Ag nanofibers were obtained via a nontemplate route when ascorbic acid was used as a relatively weak reductant. An electrical transfer and switching device was built with the obtained Ag2S and Ag nanofiber bundles, utilizing the unique ion‐conductor nature of Ag2S and revealing their potential applications in electronics. 相似文献
72.
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74.
Xin Qi Salapaka M.V. Voulgaris P.G. Khammash M. 《Automatic Control, IEEE Transactions on》2004,49(10):1623-1640
In this paper, the design of controllers that incorporate structural and multiobjective performance requirements is considered. The control structures under study cover nested, chained, hierarchical, delayed interaction and communications, and symmetric systems. Such structures are strongly related to several modern-day and future applications including integrated flight propulsion systems, platoons of vehicles, micro-electro-mechanical systems, networked control, control of networks, production lines and chemical processes. It is shown that the system classes presented have the common feature that all stabilizing controllers can be characterized by convex constraints on the Youla-Kucera parameter. Using this feature, a solution to a general optimal performance problem that incorporates time domain and frequency domain constraints is obtained. A synthesis procedure is provided which at every step yields a feasible controller together with a measure of its performance with respect to the optimal. Convergence to the optimal performance is established. An example of a multinode network congestion control problem is provided that illustrates the effectiveness of the developed methodology. 相似文献
75.
Interfacial hybridization kinetics of oligonucleotides immobilized onto fused silica surfaces 总被引:3,自引:0,他引:3
Jiang Zeng Amer Almadidy James Watterson Ulrich J. Krull 《Sensors and actuators. B, Chemical》2003,90(1-3):68-75
Fused silica optical fibers have been used in an intrinsic mode optical configuration as biosensors for fluorescence based detection of hybridization of nucleic acids. In this work, the kinetics of hybridization of single-stranded oligonucleotides that were covalently immobilized were studied. The probe DNA was dT20, and the target was Fluorescein-labeled non-complementary (dT20) or complementary (dA20) oligonucleotide. Chronofluorimetric monitoring of the adsorption and hybridization processes was used to investigate oligonucleotide films of different density, in different salt concentrations, at temperatures of 25 and 40 °C, with the concentration of the target DNA being 0.005–0.1 μM. Mathematical models based on first- and second-order Langmuir adsorption have been examined to describe both the adsorption and the hybridization processes. Experimental data were processed using the models, and the hybridization kinetics were calculated. Hybridization kinetics on these optical fiber DNA sensors was found to be up to three orders faster than results presented for a number of other experiments using different immobilization chemistries. 相似文献
76.
Longjie Zhou A. Zimmermann Yu-Ping Zeng F. Aldinger 《Journal of Materials Science》2004,39(8):2675-2681
The bipolar electric fatigue behaviour of antiferroelectric ceramics with the composition of Pb0.88Ba0.10La0.02(Zr0.55Sn0.35Ti0.10)O3 was investigated under various cycling fields. The material exhibits a degradation in the maximum field induced strain, a diffuse AFE-FE phase transition and an enhancement in the diffusion character of the FE-AFE phase transition due to electric cycling. Those variations increase with cycle number, indicating a logarithmic fatigue up to 108 cycles. There is no indication for the variations to be recovered, and the symmetry of the negative and positive parts of the strain hysteresis loops still remains. Higher cycling field results in a stronger deterioration of the maximum field induced strain and a larger extent of diffusion in AFE-FE and FE-AFE phase transitions. The normalized maximum strain shows nearly the same scale of degradation when the materials are cycled at various electric fields. After a heat treatment at 500°C for 1 h, the variations in the AFE-FE and FE-AFE phase transition due to cycling disappear, whereas the maximum strain resumes almost to its original value. Electrochemical variations are considered to contribute to the main fatigue mechanism for the material under investigation. 相似文献
77.
We have fabricated and tested a high-Tc dc-SQUID magnetometer patterned on a YBCO thin film deposited on a SrTiO3 bicrystal substrate. The measurement of noise spectrum at 77 K showed that the magnetometer has a white noise of 333 fT/Hz1/2 without superconducting shield, corresponding to a flux sensitivity of 14.5 μΦ0/Hz1/2. We constructed a test system for eddy current non-destructive evaluation of conducting aluminum plates by using the magnetometer. Flaws over 10 mm below the surface can be clearly identified. By mapping the magnetic field distribution, we can locate the flaw position. The signals caused by flaw were expanded due to the use of double-D type driving coil with a wider central slit. The experimental results confirmed that this test system could operate in a magnetic unshielded environment. 相似文献
78.
An innovative method for modelling biological processes under anaerobic conditions is presented and discussed. The method is based on titrimetric and off-gas measurements. Titrimetric data is recorded as the addition rate of hydroxyl ions or protons that is required to maintain pH in a bioreactor at a constant level. An off-gas analysis arrangement measures, among other things, the transfer rate of carbon dioxide. The integration of these signals results in a continuous signal which is solely related to the biological reactions. When coupled with a mathematical model of the biological reactions, the signal allows a detailed characterisation of these reactions, which would otherwise be difficult to achieve. Two applications of the method to the enhanced biological phosphorus removal processes are presented and discussed to demonstrate the principle and effectiveness of the method. 相似文献
79.
建立垂直管吸收器管内泡式吸收过程中传热传质的数学物理模型,对其泡式吸收过程进行数值研究,获得泡式吸收方式的一些传热传质特性,为吸收器的优化设计提供一定理论指导。 相似文献
80.
一、概况南平市种猪场位于延平区浆甲村 ,距市区 13km ,地处 316国道旁 ,面临沙溪口库湾边。年存栏猪760 0头 ,其中母猪 60 0头 ,后备种猪 2 5 0 0头 ,商品猪 4 5 0 0头 ,是闽北集种猪、商品猪生产及科研繁育于一体的副食品基地之一。该场日排猪粪便污水约140t,未建沼气工程前 ,直接排入水库 ,严重污染水体。1999年 ,种猪场采用厌氧发酵技术 ,处理猪粪便污水 ,兴建 4× 2 0 0m3沼气工程 ,技术落后 ,基本属于农村户用水压式沼气池的简单放大 ,猪粪便污水直接进入厌氧发酵池 ,出水直接排入水库。工程设计的主要问题是 :1 不设前处理装置 ,冲洗… 相似文献