Stubs

Distribution by Scientific Domains

Kinds of Stubs

  • tuning stub


  • Selected Abstracts


    Cyclic tests of post-tensioned precast CFT segmental bridge columns with unbonded strands

    EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2006
    Chung-Che Chou
    Abstract Two ungrouted post-tensioned, precast concrete-filled tube (CFT) segmental bridge columns were tested under lateral cyclic loading to evaluate the seismic performance of the column details. The specimens included a load stub, four equal-height circular CFT segments, and a footing. Strands were placed through the column and post-tensioned to provide a precompression of the column against the footing. One specimen also contained energy-dissipating devices at the base to increase the hysteretic energy. The test results showed that (1) both specimens could develop the maximum flexural strength at the design drift and achieve 6% drift with small strength degradation and residual displacement, (2) the proposed energy-dissipating device could increase energy dissipation in the hysteresis loops, and (3) the CFT segmental columns rotated not only about the base but also about the interface above the bottom segment. This study proposed and verified a method to estimate the experimental flexural displacement using two plastic hinges in the segmental column. Copyright 2005 John Wiley & Sons, Ltd. [source]


    Effects of parasitic resonance on a vertical transition in multilayer printed circuit boards

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2010
    Sung Tae Choi
    Abstract This article reports on parasitic resonance effects of a ground plane with/without a ground opening underneath a signal via with an open stub on the performance of a vertical transition in a multilayer printed circuit board. An equivalent circuit model that accounts for the parasitic resonance due to the open stub inductance and the parasitic capacitance is developed and verified with the measured and simulated results. The fabricated transition exhibits a return loss better than about 10 dB and an insertion loss less than 1.9 dB up to 21.5 GHz. A good agreement is observed between measured and simulated results. 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 2098,2100, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25404 [source]


    Design of a planar ultra-wideband miniature monopole antenna for wireless USB dongle devices

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2010
    Yu-Chia Chang
    Abstract This article proposes a 3.1,5 GHz ultra-wideband antenna, defined by a ,10 dB return loss. The simplified planar antenna structures, compact size, and low profile make it profitable to the application of the embedded antenna in wireless universal serial bus dongle devices. The slit shape on the monopole radiator is tuned for miniature antenna size. A parasitic stub on the ground is adopted to increase antenna bandwidth for achieving 3.1,5 GHz impedance bandwidth. To reduce manufacturing cost and practical fabrication, we also propose a simplified rectangular antenna structure. It is found that wideband characteristics of the simplified rectangular structure antenna are similar to that of semicircular base structure. Finally, the antenna prototypes are fabricated and the antenna characteristics are measured. The radiation patterns are omnidirectional in azimuth cut. Moreover, the S -parameter of antenna characteristics has been measured. The consistency between the simulated results and the measurement results confirms the practicability of these techniques. 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1013,1016, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25121 [source]


    60 GHz SoC/SoP radio system for high data-rate transmission

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2010
    K. C. Eun
    Abstract We present the 60 GHz CMOS and system-on-package (SoP) research activities in Korea Advanced Institute of Science and Technology for high data-rate and short-range wireless communication. A low-power single-chip resonant frequency CMOS receiver for 60 GHz mobile terminals consists of four-stage current reuse LNA, resistive mixer, Ka-band low-phase noise VCO, high-suppression frequency doubler, and two-stage current reuse drive amplifiers. The receiver conversion gain and input P1dB are ,9.5 dB and ,12.5 dBm, respectively, with a size of 2.67 0.75 mm2 and power consumption of 21.9 mW. The integration and communication tests of a transmitter/receiver (Tx/Rx) radio have been demonstrated at a data rate of 3 Gbps for short-range transmission and with a communication distance of over 3.5 m at 650 Mbps data rate. The design and fabrication of mmW subcircuits, such as low-loss transmission lines and transitions with noble air cavity structures, a high-Q resonator using zigzagged dual-row via posts and a ,/4 short stub, and the monolithic integration of band-pass filter and antennas, have been performed for low-temperature cofired ceramic SoP integration with a size of 37 11 mm2 for the whole Tx or Rx radio. 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 667,673, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25024 [source]


    A compact low-pass filter with double-step impedance shunt stub and defected ground structure for wideband rejection

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2010
    Jae-Kwan Lee
    Abstract In this letter, a compact low-pass filter (LPF) with wideband rejection using double-step impedance shunt stub (SISS) and barbell-type defected ground structure (DGS) is presented. This proposed LPF has similar characteristics in bandwidth, but good wideband rejection and cutoff sharpness compared with the same size conventional LPF, using SISS and conventional DGS. The size reduction of the proposed LPF is about 23% more than the conventional one. Good agreements are achieved between the simulated and measured results. 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 132,134, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24883 [source]


    Compact UWB planar monopole antenna with band-notch function

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2009
    Li-Na Zhang
    Abstract A new band-notch ultrawideband (UWB) printed monopole antenna is proposed, where the band-notch characteristic is realized by introducing a microstrip feeder with a tuning stub. The simulation results agree well with the measured ones, showing that the proposed antenna provides an operating band ranging from 2.9 to 11.6 GHz, a notched band from 5.0 to 5.9 GHz, and a good omni-directional far-field radiation in the H-plane. 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1908,1911, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24507 [source]


    Ultra-wideband slot antenna with band-notch characteristics for wireless USB dongle applications

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2009
    Deepti Das Krishna
    Abstract A compact ultra-wideband (UWB) printed slot antenna is described, suitable for integration with the printed circuit board (PCB) of a wireless, universal, serial-bus dongle. The design comprises of a near-rectangular slot fed by a coplanar waveguide (CPW) printed on a PCB of size 20 30 mm2. It has a large bandwidth covering the 3.1,10.6 GHz UWB band, with omnidirectional radiation patterns. Further, a notched band centered at 5.45 GHz wireless local area network bands is obtained within the wide bandwidth by inserting a narrow slot inside the tuning stub. Details of the antenna design are described, and the experimental results of the constructed prototype are presented. The time domain studies on the antenna shows a linear phase response throughout the band except at the notched frequency. The transient analysis of the antenna indicates very little pulse distortion confirming its suitability for high speed wireless connectivity. 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1500,1504, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24385 [source]


    Design of dual-band antenna with U-shaped open stub for WLAN/UWB applications

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2009
    Jung N. Lee
    Abstract In this article, we have proposed a dual-band antenna with U-shaped open stub for wideband local area network (WLAN)/ultra wideband (UWB) applications. The designed dual-band antenna consists of two semicircle radiating patches, a rectangular slot separating the two semicircles, one step for impedance matching, and coplanar waveguide (CPW) feeding. Two kinds of prototypes (CPW-fed UWB antenna and the dual-band antenna with U-shaped open stub) are fabricated and measured. Parametric studies and radiation characteristics for the two antennas are presented. The designed antenna has the figure-of-eight radiation pattern, wide bandwidth, and negligible dispersion over the operating frequency band. 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 284,289, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24033 [source]


    A novel implementation of composite right/left-handed transmission line

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2008
    Jia-Jun Ma
    Abstract A novel composite right/left-handed transmission line is presented in this letter. The proposed CRLH structure can be considered as a CPW version composed with a pair of parallel spiral interdigital and a conjunctive stub. The spiral interdigital enlarges the series capacitance, and the adjustable conjunctive stub increases the shunt inductance. So, this structure is simpler and more compact compared with the conventional one. Its left-handed material property is confirmed by simulation and measurement results. 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2379,2381, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23672 [source]


    Compact ultrawideband square slot antenna with an asymmetric protruding stub

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2008
    Jen-Yi Shiu
    Abstract A new compact ultra-wideband (UWB) square slot antenna fed by a coplanar waveguide (CPW) is proposed. A large impedance bandwidth of more than 13 GHz (2.8,16 GHz) was obtained by asymmetrically widening the tuning stub that is extended from the signal strip of the CPW into the square slot. The larger and smaller widened parts of the asymmetric tuning stub can be easily adjusted to achieve good impedance matching in the lower and upper regions, respectively, of the entire VSWR , 2 band. The simple design procedure along with reasonably agreed measured and simulated results is presented. 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1776,1779, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23544 [source]


    Novel dual-band microstrip filter using complementary split-ring resonators

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2008
    Xin Lai
    Abstract On the basis of the double resonant property of the complementary split-ring resonators (CSRRs), a novel dual-band microstrip filter is designed, making use of CSRRs as resonant unit and T-shaped stub as feeding structure. More than one transmission zeros are formed due to the cross coupling between the CSRR cells and the T-shaped feeding lines, which have greatly improved the out-of-band property. To validate the proposed method, a dual-band filter with two passbands of 2.4,2.6 GHz and 3.8,4.3 GHz is fabricated and measured, which has a low insertion loss and a high out-of-band rejection. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 7,10, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22983 [source]


    A CPW-fed staircase monopole UWB antenna with band-notched frequency in the WLAN band

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2007
    Sang Joong Kim
    Abstract A coplanar waveguide (CPW)-fed ultra-wideband staircase monopole antenna with a frequency-notch characteristic is presented. The proposed antenna consists of a planar four-step staircase rectangular monopole with a ground short-circuited stub, open stubs at the ground part, and two-step impedance transformer at the CPW-fed line. The impedance bandwidth is increased due to an offset feeding technique and one-side ground notch. The notched frequency band can be accomplished by means of the method that involves adding open stubs at the ground. The measured results are in good agreement with the simulated ones. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2545,2547, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22775 [source]


    Surface-mount loop antenna for AMPS/GSM/DCS/PCS operation in the PDA phone

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2007
    Wei-Yu Li
    Abstract A surface-mount loop antenna very suitable for application in the mobile devices such as the PDA (Personal Digital Assistant) phone for quad-band operation is presented. The antenna comprises of a loop metal pattern for generating two wideband resonant modes at about 900 and 1800 MHz to cover the AMPS/GSM/DCS/PCS bands and a central coupling stub as the feed structure. Although quad-band operation is obtained, the antenna occupies a small volume of 7 8 60 mm3 or about 3.4 cm3 only and is easy to be embedded inside the PDA phone as an internal antenna. Details of the proposed surface-mount loop antenna are presented and discussed. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2250,2254, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22700 [source]


    Fabrication and measurement of triangular-slot antenna for triple-band (2.4/5.2/5.8 GHz) antenna with rectangular tuning stub

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2007
    JoongHan Yoon
    Abstract In this paper, a novel design of a triangular-slot antenna with rectangular tuning stub for 2.4/5.2/5.8 GHz triple-band applications is presented. The prototype consists of a triangular slot and rectangular tuning stub. Results show that the impedance matching of the proposed antenna is greatly affected by the feed gap width. Experimental results indicate that the impedance bandwidth (VSWR 1:2) of the proposed antenna is about 423 MHz for the 2.4-GHz band and 1.92 GHz for the 5-GHz band. The simulated and experimental results for the return loss, radiation patterns, and gains are presented and discussed. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1793,1797, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22621 [source]


    Design of triangular slot antenna for triple-band (2.4/5.2/5.8 GHz) antenna with fork-like tuning stub

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2007
    J. H. Yoon
    Abstract A novel design for a triangular slot antenna with fork-like tuning stub for 2.4/5.2/5.8 GHz triple-band applications is presented in this article. The prototype consists of a triangular slot and a fork-like tuning stub. The triangular slot is fed by a 50-, microstrip line with a fork-like tuning stub, which is printed on the opposite side of the microwave substrate. As seen in the experimental results, the impedance bandwidth (VSWR 1:2) of the proposed bandwidth is about 550 MHz for the 2.4-GHz band and 1.736 GHz for the 5-GHz band. This is a microstrip antenna for IEEE 802.11a/b wireless local area networks applications. Simulated and experimental results for the return loss, radiation patterns, and gains are presented and discussed. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1561,1565, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22499 [source]


    Broadband circularly polarized wide-slot antenna

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2007
    R. P. Xu
    Abstract A new broadband single-fed circularly polarized (CP) wide-slot antenna is presented in the letter. The antenna is composed of a wide-slot, with a T-shaped stub and a microstrip T-junction. The CP operation is realized by the interaction from the T-shaped stub on the wide-slot and the T-junction. The antenna has been investigated numerically and experimentally. Measured result shows that the antenna has an impedance bandwidth of 58% and a 3-dB bandwidth of axial ratio of 22.2%. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1005,1007, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22337 [source]


    Design of bandstop filters using discrete-time notch filter, two-section stub, and frequency-scaling method

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2007
    Ching-Wen Hsue
    Abstract A new method for the design of a bandstop filter is presented. The two-section open stub is employed to emulate a notch filter in the discrete-time domain. A cascade connection of two-section open stubs with proper frequency scaling serves to represent a bandstop filter of wider stopband bandwidth. Experimental results are presented to illustrate the validity of this design method. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1098,1101, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22356 [source]


    Improvement of the resonant characteristics of the short-ended stub by the optimal arrangement positions of via-holes

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2007
    Ifong Wu
    Abstract A method for improving the resonant characteristic of the short-ended stub is proposed by locating the via-holes on the optimal position on the ground. In the first step, the optimal length of the stub at 1 GHz is evaluated by comparing the numerical calculated result and the measured result (used the fabricated stub), which is based on the theoretical calculation, and the resonant characteristics shifted to the lower frequency regions. These shifting phenomena of the resonant characteristics are caused by the via-hole. When the via-hole is arranged on the substrate, the via-hole becomes part of the stub, and the length of the stub becomes longer than the theoretical calculation. As a result, a good agreement between both results is achieved when the stub length is 27.43 mm, and hence the optimal length of the stub is confirmed. For the second step, the optimal arrangement position of the via-holes is evaluated by using current distribution on the stub model. In this study, we applied the Green's function method to obtain the current distribution. The improvement of resonant characteristic is achieved by arranging the via-holes on the place where the currents concentrate. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 642,645, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22202 [source]


    Ultrawideband monocycle pulse generator with dual resistive loaded shunt stubs

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2007
    Tzyh-Ghuang Ma
    Abstract An ultrawideband (UWB) monocycle pulse generator with dual resistive loaded shunt stubs is present in this article. The proposed pulse generator consists of a step recovery diode (SRD), a Schottky diode, a pair of resistive loaded stubs, and a pair of short-circuited stubs. By introducing an additional resistive loaded stub between the SRD and the Schottky diode, the ringing tail of the impulse waveform can be substantially suppressed and the resultant monocycle pulse is well-behaved with very low ringing level. The measurement result demonstrates a monocycle pulse with peak-to-peak amplitude of 550 mV, pulsewidth of 320 ps, ringing level of as low as ,22 dB, and good pulse symmetry. This pulse generator is suitable for various UWB applications. 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 459,462, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22145 [source]


    Microstrip dual-band bandpass filter using slow-wave resonators for WLAN applications

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2007
    Xuehui Guan
    Abstract A dual-band bandpass filter using microstrip slow-wave resonators is developed for wireless local area network applications. The fundamental and higher order resonant harmonics of a microstrip open-loop resonator are analyzed against the length of the loading open stub. Then a dual-band bandpass filters is designed in the form of slow-wave open-loop resonators. A zero-degree feed structure is employed to produce transmission zeros near the passband to increase the rate of attenuations, and a quarter-wavelength feed line for impedance matching is added to get desired external quality factor at the input and output. The theoretical analysis and design procedures are successfully verified by experimental results. 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 14,16, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22055 [source]


    Coplanar to microstrip transitions for on-wafer measurements

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2007
    Yi Wang
    Abstract Two types of via-free coplanar line to microstrip transitions are designed and tested for on-wafer measurements. The transitions are designed to fit coplanar ground-signal-ground probes. They are taper transitions with capacitive ground patches and radial stub transitions. Both structures are easy implemented and exhibit wideband transmission. The performance of the optimized taper transition is among the best demonstrated in terms of a return loss of less than ,20 dB from 5 to 15.5 GHz; this is even superior to the radial stub designs. Design information is given, which is based on full-wave simulations for the taper transition, and analytical formulations for the radial stub. The increasing bandwidth with increased angle of the radial stub is observed. The transition structures and design guidelines addressed can be used for on-wafer measurements of a wide range of microstrip circuits. 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 100,103, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22056 [source]


    Band-notched ultra-wideband square slot antenna

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2006
    Horng-Dean Chen
    Abstract An ultra-wideband (UWB) square slot antenna with a band-notched characteristic is presented. The proposed antenna has a simple configuration and is easy to construct. The ultra-wideband operation is realized by loading an offset rectangular stub at the end of the microstrip feed line. The band-notched characteristic is achieved by embedding an U-like slot in the rectangular stub. The notched frequency band can be controlled by adjusting the length of the U-like slot. A design example for an UWB (3.1,10.6 GHz) square slot antenna with a notched frequency band at 5 GHz is demonstrated. 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2427,2429, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21966 [source]


    Compact dual-band LTCC meander-chip antenna with gap stub for mobile handsets

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2005
    Young Do Kim
    Abstract This paper presents design simulation, implementation, and measurement of a miniature GPS/K-PCS dual-band LTCC chip antenna for mobile-communication handsets. The dimensions of the LTCC chip antenna are 9 15 1.2 mm. The lower meander-type antenna is tuned to the lower-frequency (GPS) band and the upper meander antenna with via-hole connection contributes to the higher-frequency (K-PCS) band. In order to lower the resonant frequency for the GPS band, a printed modified meander antenna with gap stub is used for integration with K-PCS band operation. The measured impedance bandwidths (VSWR , 2) are 55 and 120 MHz at the resonant frequency, respectively. 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 431,433, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21007 [source]


    Design of transmission line filters and matching circuits using genetic algorithms

    IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 6 2007
    Hirofumi Sanada Member
    Abstract A method for designing microwave filters and impedance matching circuits using transmission lines is presented. Transmission line filters with shunt-connected open circuit stubs and continuously varying transmission line matching circuits are described in detail. The proposed method is based on genetic algorithms and can effectively be applied to various filter and matching circuit design problems without increasing theoretical and computational complexity. Design examples are provided, and the proposed method is demonstrated to be effective in designing transmission line filters and matching circuits. Copyright 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]


    Scanning Electron Microscope Analysis of Internal Adaptation of Materials Used for Pulp Protection under Composite Resin Restorations

    JOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 2 2005
    MARIA INEZ LEMOS PELIZ DDS
    ABSTRACT Purpose:: The aim of this study was to evaluate the interfacial microgap with different materials used for pulp protection. The null hypothesis tested was that the combination of calcium hydroxide, resin-modified glass ionomer, and dentin adhesive used as pulp protection in composite restorations would not result in a greater axial gap than that obtained with hybridization only. Materials and Methods: Standardized Class V preparations were performed in buccal and lingual surfaces of 60 caries-free, extracted human third molars. The prepared teeth were randomly assessed in six groups: (1) Single Bond (SB) (3M ESPE, St. Paul, MN, USA); (2) Life (LF) (Kerr Co., Romulus, MI, USA) + SB; (3) LF + Vitrebond (VT) (3M ESPE) + SB; (4) VT + SB; (5) SB + VT; (6) SB + VT + SB. They were restored with microhybrid composite resin Filtek Z250 (3M ESPE), according to the manufacturer's instructions. However, to groups 5 and 6, the dentin bonding adhesive was applied prior to the resin-modified glass ionomer. The specimens were then thermo-cycled, cross-sectioned through the center of the restoration, fixed, and processed for scanning electron microscopy. The specimens were mounted on stubs and sputter coated. The internal adaptation of the materials to the axial wall was analyzed under SEM with 1,000 magnification. Results: The data obtained were analyzed with nonparametric tests (Kruskal-Wallis, p V .05). The null hypothesis was rejected. Calcium hydroxide and resin-modified glass ionomer applied alone or in conjunction with each other (p < .001) resulted in statistically wider microgaps than occurred when the dentin was only hybridized prior to the restoration. [source]


    Influence of plant silicon and sugarcane cultivar on mandibular wear in the stalk borer Eldana saccharina

    AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2009
    Olivia L. Kvedaras
    Abstract 1,Silicon can increase the resistance of plants to attack by herbivorous insects. The present study aimed to determine the effect of silicon and cultivar on mandibular wear in larvae of the sugarcane stalk borer Eldana saccharina Walker (Lepidoptera: Pyralidae). 2,Four sugarcane cultivars, resistant (N21, N33) and susceptible (N11, N26) to E. saccharina were grown in a pot trial in silicon deficient river sand, with (Si+) and without (Si,) calcium silicate. Individual third-instar larvae were confined on the sugarcane stalk at three known feeding sites (leaf bud, root band and internode) and left to feed for 21 days. 3,Eldana saccharina larval heads were mounted on stubs, with the mandibles oriented horizontally and photographed under a scanning electron microscope. Mandibular wear was measured from the digital images using a quantitative method. 4,Although there was a trend for increased wear in larvae that developed on Si+ cane, no significant effect of silicon, cultivar or site on mandibular wear of E. saccharina was shown. 5,This is the first study to accurately and quantitatively measure the mandibular wear of an insect fed on Si+ plants. [source]


    DIFFERENCES IN POLYSACCHARIDE STRUCTURE BETWEEN CALCIFIED AND UNCALCIFIED SEGMENTS IN THE CORALLINE CALLIARTHRON CHEILOSPORIOIDES (CORALLINALES, RHODOPHYTA),

    JOURNAL OF PHYCOLOGY, Issue 3 2010
    Patrick T. Martone
    The articulated coralline Calliarthron cheilosporioides Manza produces segmented fronds composed of calcified segments (intergenicula) separated by uncalcified joints (genicula), which allow fronds to bend and reorient under breaking waves in the wave-swept intertidal zone. Genicula are formed when calcified cells decalcify and restructure to create flexible tissue. The present study has identified important differences in the main agaran disaccharidic repeating units [,3)-,- d -Galp (1, 4)-,- l -Galp(1,] synthesized by genicular and intergenicular segments. Based on chemical and spectroscopical analyses, we report that genicular cells from C. cheilosporioides biosynthesize a highly methoxylated galactan at C-6 position with low levels of branching with xylose side stubs on C-6 of the [,3)-,- d -Galp (1,] units, whereas intergenicular segments produce xylogalactans with high levels of xylose and low levels of 6- O -methyl ,- d -Gal units. These data suggest that, during genicular development, xylosyl branched, 3-linked ,- d -Galp units present in the xylogalactan backbones from intergenicular walls are mostly replaced by 6- O -methyl -d- galactose units. We speculate that this structural shift is a consequence of a putative and specific methoxyl transferase that blocks the xylosylation on C-6 of the 3-linked ,- d -Galp units. Changes in galactan substitutions may contribute to the distinct mechanical properties of genicula and may lend insight into the calcification process in coralline algae. [source]


    An optimum superconducting ultra-wideband bandpass filter at VHF band

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2010
    Wei Chen
    Abstract A highly selective superconducting ultra-wideband filter with a passband from 125 to 260 MHz is designed and demonstrated using a microstrip structure. The filter is designed according to a circuit model for an optimum short-circuited stub transmission-line filter and consists of 10 shunt short-circuited stubs separated by connecting lines. The short-circuited stubs are quarter-wavelength long, and the connecting lines are half-wavelength long. The filter is realized on two 3-inch YBCO/LaAlO3 substrates, which are connected by two bonding wires. The short-circuited stubs are grounded via two grounding pads that are attached to the box wall by a number of SiAl bonding wires. The measured results exhibit a selective filtering characteristic equivalent to a 19-pole Chebyshev filter and a low insertion loss of less than 0.1 dB at center frequency without tuning. Furthermore, the experimental results of the filter are in good agreement with the simulated ones. 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2639,2641, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25571 [source]


    An ultra-wide stopband microstrip bandpass filter

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2010
    Guangming Zheng
    Abstract This article develops a novel microstrip bandpass filter with ultra-wide stopband. With the assistance of open stubs and interdigital capacitors, a very wide stopband with a sufficient rejection level can be achieved easily. Detailed design and synthesis procedures are provided. Moreover, the electromagnetic simulator ansoft designer v3 is used, and the prototype of the bandpass filter is fabricated and measured. Good agreement between measured and theoretically predicted results demonstrates feasibility of the proposed filter. 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2218,2221, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.25426 [source]


    High-performance UWB filter with a controllable notched band

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2010
    Chun-Ping Chen
    Abstract This article presents a design of a high-performance ultra-wideband (UWB) bandpass filter with a controllable notched band. Firstly, a UWB filter consisting of a stepped-impedance resonator (SIR) and two shunt short-circuited stubs is synthesized. Then, a narrow controllable notched band is introduced by a coupled external SIR. To be highlighted as an attractive advantage, as the characteristics of the UWB filter are not deteriorated by the placement of the external resonator, no further adjustments is needed for the synthesized UWB filter in this design. As an example, an (Federal Communications Commission) FCC UWB filter with a WLAN notch band is designed, simulated, and fabricated. A good agreement between the measured results and predicted ones validates the newly proposed design scheme and the filter prototype. 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1842,1846, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25354 [source]