Waveguide filter with improved stopband response using transversal slots

In this article, the design and realization of waveguide filter with improved stop‐band response is presented. By inserting transversal slots at the proper position of cavities, without disturbing the field distribution of the dominant mode, the second longitudinal resonant modes are radiated out. This caused the out‐of‐band frequency response of the filter to be improved. The validity of the proposed technique is confirmed by comparison between measurement values and simulation results from the finite element method through the commercial software (high frequency structure simulator). Also, to assure electromagnetic compatibility the slot surfaces are covered by absorbing material. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Scalable arrays of chemical vapor sensors based on DNA-decorated graphene

Arrays of chemical vapor sensors based on graphene field effect transistors functionalized with single-stranded DNA have been demonstrated. Standard photolithographic processing was adapted for use on large-area graphene by including a metal protection layer, which protected the graphene from contamination and enabled fabrication of high quality field-effect transistors （GFETs）. Processed graphene devices had hole mobilities of 1,640 ± 250 cm2.V-1.s-1 and Dirac voltages of 15 ± 10 V under ambient conditions. Atomic force microscopy was used to verify that the graphene surface remained uncontaminated and therefore suitable for controlled chemical functionalization. Single-stranded DNA was chosen as the functionalization layer due to its affinity to a wide range of target molecules and π-π stacking interaction with graphene, which led to minimal degradation of device characteristics. The resulting sensor arrays showed analyte- and DNA sequence-dependent responses down to parts-per-billion concentrations. DNA/GFET sensors were able to differentiate among chemically similar analytes, including a series of carboxylic acids, and structural isomers of carboxylic acids and pinene. Evidence for the important role of electrostatic chemical gating was provided by the observation of understandable differences in the sensor response to two compounds that differed only by the replacement of a （deprotonating） hydroxyl group by a neutral methyl group. Finally, target analytes were detected without loss of sensitivity in a large background of a chemically similar, volatile compound. These results motivate further development of the DNA/graphene sensor family for use in an electronic olfaction system.     

EN81-1-1和EN81-2的修订状态和建议的变更

正如大家所知道,EN81是最基础的安全方面的标准,广泛应用于全世界很多地方。1EN81标准体系（1）电梯标准体系结构表如图1,包括：技术规范、评价体系、斜行电梯、远程监控、货梯、地震情况下电梯要求等各种规范。其中EN81-80,安全性提高,已经转化为中国国标。     

Complete dynamic modeling and approximate state space equations of the flexible link manipulator

This work treats the problem of dynamic modeling and state space approximation for robotic manipulators with flexibility. Case studies are planar manipulators with a single flexible link together with clamped-free ends and tip mass conditions. In this paper, complete dynamic modeling of the flexible beam without premature linearization in the formulation of the dynamics equations is developed, whereby this model is capable of reproducing nonlinear dynamic effects, such as the beam stiffening due to the centrifugal and the Coriolis forces induced by rotation of the joints, giving it the capability to predict reliable dynamic behavior. On the other hand, in order to show the joint flexibility effects on the model dynamic behaviors, manipulator with structural and joint flexibility is considered. Thus, a reliable model for flexible beam is then presented. The model is founded on two basic assumptions: inextensibility of the neutral fiber and moderate rotations of the cross sections in order to account for the foreshortening of the beam due to bending. To achieve flexible manipulator control, the standard form of state space equations for a flexible manipulator system (flexible link and actuator) is very important. In this study, finite difference method for discretization of the dynamic equations is used and the state space equations of the flexible link with tip mass considering complete dynamic of the system are obtained. Simulation results indicated substantial improvements on dynamic behavior and it is shown that the joint flexibility has a considerable effect on the dynamic behavior of rotating flexible arm that should not be simply neglected. The effects of tip mass is proved to be increasing the elastic deformations?? amplitudes and increasing stability.     

Increasing the antioxidant activity of green tea polyphenols in the presence of iron for the reduction of graphene oxide

An easy method for green and low-temperature (40 °C) reduction of graphene oxide (GO) by increasing the antioxidant activity of green tea polyphenols (GTPs) in the presence of iron was developed. The reduction level (obtained by X-ray photoelectron spectroscopy) and electrical conductivity (obtained by current–voltage measurement) of the GO sheets reduced by GTPs in the presence of iron were comparable to those of hydrazine-reduced GO and much better than those of the GO reduced by only GTPs (in the absence of iron) at reduction temperatures of 40–80 °C. Raman spectroscopy indicated that application of GTPs in the presence of iron, in contrast to hydrazine, resulted in better recovering of the sp²-hybridized structure of the sheets. The lasting water dispersion of the polyphenolic-reduced GO sheets in the presence of iron was assigned to π–π adsorption of Fe²⁺-polyphenol radicals on surface of the reduced sheets. A mechanism describing the role of iron in the reduction of the GO by epicatechin gallate and epigallocatechin gallate of green tea was also proposed.     

Electrical conductivity of single walled and multiwalled carbon nanotube containing wool fibers

The main purpose of this study was producing conductive wool fabric applying carbon nanotubes. Raw and oxidized wool samples were treated with carbon nanotubes in the impregnating bath in the presence of citric acid as a crosslinking agent and sodium hypophosphite as a catalyst while sonicating them in the ultrasonic bath. Electrical resistance, washing durability, and color variation of treated samples were assessed. Through SEM images, the surface morphology of treated samples was studied confirming the surface coating through carbon nanotubes. According to the results, the electrical resistance of treated wool with carbon nanotubes reduced substantially. However, the single‐walled carbon nanotubes are more useful to increase the conductivity. In addition, the wool color changed into gray after the treatment. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Self-cleaning wool: effect of noble metals and silica on visible-light-induced functionalities of nano TiO2 colloid

This study intends to enhance the functionality of titanium dioxide (TiO₂) nanoparticles applied to wool fabrics under visible light. Herein, TiO₂, TiO₂/SiO₂, TiO₂/Metal, and TiO₂/Metal/SiO₂ nanocomposite sols were synthesized and applied to wool fabrics through a low-temperature sol–gel method. The impacts of three types of noble metals, namely gold (Au), platinum (Pt), and silver (Ag), on the photoefficiency of TiO₂ and TiO₂/SiO₂ under visible light were studied. Different molar ratios of Metal toTiO₂ (0.01, 0.1, 0.5, and 1%) were employed in synthesizing the sols. Photocatalytic efficiency of fabrics was analyzed through monitoring the removal of red wine stain and degradation of methylene blue under simulated sunlight and visible light, respectively. Also, the antimicrobial activity against Escherichia coli (E. coli) bacterium and the mechanical properties of fabrics were investigated. Through applying binary and ternary nanocomposite sols to fabrics, an enhanced visible-light-induced self-cleaning property was imparted to wool fabrics. It was concluded that the presence of silica and optimized amount of noble metals had a synergistic impact on boosting the photocatalytic and antimicrobial activities of coated samples. The fabrics were further characterized using attenuated total reflectance, energy-dispersive X-ray spectrometry, and scanning electron microscopy images.     

Substrate‐integrated waveguide band pass filters with frequency‐dependent coupling elements

An effective technique to improve the stop‐band frequency response of direct‐coupled resonators in substrate‐integrated waveguide (SIW) technology is introduced. Regular inductive‐iris filters in SIW technology are supplemented with H‐plane frequency‐dependent inverters which not only create transmission zeros but also serve as the proper impedance inverter. A synthesis technique is introduced to prescribe transmission zeros at finite frequencies on either side of the pass band, symmetrically or asymmetrically. Two different topologies of frequency‐dependent inverters for X‐band SIW band pass filters demonstrate that attenuation poles can be created on both side of the passband and significantly improve the filters' stop‐band performences. Measurements confirm the validity of the presented design approach. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:237–242, 2014.     

Spurious‐response suppression of substrate integrated waveguide filters using multishape resonators and slotted plane structures

This article introduces effective techniques to improve the stopband frequency response of substrate integrated waveguide filters. First, a filter is constructed by using different cavity resonators which resonate at the same fundamental mode but at different high‐order modes. A cascade connection of circular and rectangular cavities is used to separate high‐order modes, because the second resonant mode of the circular cavities is more than rectangular ones. Second, inserting transverse radiating slots at the proper positions of cavities, their second longitudinal resonant modes are shifted down and effectively rejected. Third, four cells of slotted plane structure (SPS) are adopted to the top plane of the both input and output feed lines of the filter to reject the undesired passbands or improve steepness of the filter. Also, a combination of the radiation slots with SPS is used to reject the spurious responses accompanied by sharp steepness of the filter. Comparing between the measurement values and simulation results verifies the effectiveness of the proposed configurations and the hybrid technique. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.