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排序方式: 共有155条查询结果,搜索用时 15 毫秒
111.
《Photonics and Nanostructures》2014,12(4):284-290
In this paper, we present a new class of waveguide components based on the use of complementary electrically small resonators etched on metallic sheets. We first show a rectangular-to-circular waveguide transition that allows to effectively match waveguides with different cross-sections and to transform the linearly polarized TE10-mode of a rectangular waveguide into a circularly polarized TE11-mode of a circular waveguide. Then, using similar structures, we present the design and the numerical results of two power dividers and of an orthomode transducer. All these components, employing only thin metallic sheets with properly shaped slits, can be integrated in waveguide transmission systems without increasing their space occupancy. A proper set of full-wave numerical simulations proves the validity of the proposed approach. 相似文献
112.
《Photonics and Nanostructures》2014,12(4):269-278
This paper proposes a dual-band power divider operating at GHz frequencies and implemented by means of impedance transformers (also called inverters) based on lattice networks and transmission line sections. The dual-band functionality of the proposed device is achieved thanks to the composite right/left handed (CRLH) behavior of the impedance transformers, able to provide −90° and +90° phase shift at the first and second design frequencies, respectively, of the divider. By using such combination of transmission line sections and lattice networks, the characteristic impedance of the impedance transformers is roughly constant over wide bandwidths, with the results of broad operating bands. To demonstrate the possibilities of the approach, a prototype device is designed, fabricated and characterized. 相似文献
113.
Mahmoud Labib Martin Hedstr?m Magdy Amin Bo Mattiasson 《Analytical and bioanalytical chemistry》2009,393(5):1539-1544
A sensitive method for the detection of staphylococcal enterotoxin B (SEB) using a flow-injection capacitive biosensor is
presented. SEB was purified from a crude culture filtrate of Staphylococcus aureus through three chromatographic steps. The first two steps were based on ion-exchange chromatography, and the last step was
carried out on a gel filtration column. The SEB recovery values after the purification stages were 88%, 74%, and 12%, respectively.
A horseradish peroxidase labeled antistaphylococcal enterotoxin B was prepared by the periodate method and was further employed
in a sandwich-enzyme-linked immunosorbent assay (ELISA) for the determination of SEB concentrations in different samples obtained
during the processing of the crude filtrate. The capacitive biosensor could detect SEB concentrations as low as 0.3 pg ml−1 with a linearity ranging from 2.8 pg ml−1 to 2.8 ng ml−1 under optimized conditions. The response time was about 10 min. A good agreement was achieved between the developed capacitive
biosensor system and ELISA as a reference method for detection of SEB levels in different purification samples. The newly
developed sensor has the benefits of simplicity, high sensitivity, and multiple use capability. 相似文献
114.
A novel 35GHz 3dB power divider using coupled transmission line is presented. Unlike conventional Wilkinson divider circuit, only the 50 transmission lines are used in the design. The impedance matching can be achieved by coupled transmission line even mode characteristic impedance. The predicated and measured performances agree well. 相似文献
115.
Capacitive chemical sensor for fenvalerate assay based on electropolymerized molecularly imprinted polymer as the sensitive layer 总被引:2,自引:0,他引:2
Gong JL Gong FC Kuang Y Zeng GM Shen GL Yu RQ 《Analytical and bioanalytical chemistry》2004,379(2):302-307
A capacitive chemical sensor for fenvalerate is reported. By using ac impedance measurements the sensor has been based on the decrease in capacitance caused by the analyte used as the template in the formulation of an electropolymerized molecularly imprinted polymer as receptor layer. Improvement of the insulating properties of the sensor was investigated in detail. The capacitive sensor was prepared by a deposition of a self-assembled monolayer of 2-mercaptobenzimidazole (2-MBI) before electropolymerization of 2-MBI and subsequent treatment with n-dodecanethiol to eliminate pinholes and defects in the polymerized 2-MBI film. From the calibration curve concentrations of fenvalerate up to 9 g mL–1 could be detected with a linear determination range up to 5 g mL–1 and a detection limit of 0.36 g mL–1. No significant interference was observed from common pyrethroid insecticides. 相似文献
116.
The considerable growth of the world population, concomitant with an increase in environmental pollution, aggravates the antinomy between supply and demand for drinking water. Various desalination technologies have been developed to address this issue, allowing for abundant saltwater as a source for drinking water. Electrochemical desalination attracts more and more attention due to its high energy efficiency, facile operation, and low cost. Especially within the last decade, tremendous scientific progress on electrochemical desalination technologies has been made. This article reviews the development of electrochemical desalination technologies and introduces a facile classification into three generations based on the different working principles. The cell architecture, metrics, advantages, and disadvantages of other electrochemical desalination technologies are introduced and compared. 相似文献
117.
Jenny Gun Michael J. Schöning Maryam H. Abouzar Arshak Poghossian Evgeny Katz 《Electroanalysis》2008,20(16):1748-1753
A capacitive EIS (electrolyte‐insulator‐semiconductor) structure was modified with gold nanoparticles together with glucose oxidase and used as field‐effect‐based glucose biosensor using the constant capacitance mode. Co‐immobilization of ferrocene redox species resulted in a two‐fold increase of the biosensor sensitivity. The effect was explained by the hydrogen peroxide‐mediated oxidation of ferrocene resulting in a pool of charged species at the interface increasing the sensor response towards glucose. The studied approach was suggested as a general means to amplify signals from Si chip‐based field‐effect enzyme biosensors. 相似文献
118.
通过直接炭化沸石咪唑酯骨架结构材料(ZIF-8)纳米多面体,成功制备了氮掺杂介孔碳(NMCs). 采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、拉曼光谱、X射线光电子能谱(XPS)及比表面和孔隙度分析仪对其微观形貌和结构进行了表征,并对NMCs的电化学超电容性能进行了测试. 结果表明:NMCs具有规整的形貌、介孔纳米结构和较大比表面积(2737 m2·g-1);由于氮元素掺杂所赋予的优异的表面润湿性和赝电容性能,且介孔结构有利于电解质到达电极活性材料表面,NMCs表现出优异的电化学超电容性能,在1 A·g-1的电流密度下,1.0 mol·L-1H2SO4溶液中的比电容值为307 F·g-1,并具有良好的功率特性;此外,在10A·g-1的大电流密度下充放电循环5000次后,NMCs的比电容值保持率为96.9%. 相似文献
119.
碳纳米管/聚苯胺/铁氰化镍复合膜的电化学共聚制备与电容性能 总被引:2,自引:0,他引:2
采用循环伏安一步共聚法在碳纳米管修饰的铂基体上制备了电活性碳纳米管/聚苯胺/铁氰化镍(CNTs/PANI/NiHCF)复合膜.用傅立叶变换红外(FT-IR)光谱、X射线能谱仪(EDS)和扫描电镜(SEM)研究了复合膜组成及其表面形貌,并用循环伏安(CV)、恒电流充放电和电化学阻抗(EIS)等测试了复合膜的循环稳定性与电化学容量性能.研究表明:CNTs/PANI/NiHCF复合膜为三维多孔有序的网络状结构,PANI和NiHCF以纳米颗粒形式存在并沿CNTs均匀分布;在电流密度为2mA.cm-2时,CNTs/PANI/NiHCF复合膜的比容量高达262.28F.g-1,比能量为29.51Wh.kg-1,电流密度为10mA.cm-2时比功率可达10228.61W.kg-1;在2000次循环充放电过程中,复合膜的电容量仅衰减19.92%,电荷充放电效率一直保持在99%以上.CNTs/PANI/NiHCF有机-无机杂化膜具有良好的功率特性和快速充放电能力,是一种优异的超级电容器材料. 相似文献
120.
一种基于静电吸附作用的直接检测补体C3新型可再生电容型免疫传感器 总被引:2,自引:0,他引:2
通过壳聚糖/褐藻酸钠体系实现抗体在电极上的固定,制得可多次再生的电容型免疫传感器,用于补体C3的检测.先在金电极表面上组装一层半胱胺单分子层,通过戊二醛把壳聚糖修饰在金电极上,再用十二硫醇封闭电极,最后,利用壳聚糖与褐藻酸钠之间的强静电相互作用实现抗体的固定.使用交流阻抗法研究了溶液pH值和离子强度对电极膜层稳定性及对抗体固定性的影响.结果表明,所制备的传感器操作简便,易于再生,电容响应与补体C3浓度在18.2~292.5ng/mL范围内呈线性关系,检出限为9.1ng/mL. 相似文献