bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and development of a broadband amplitude compensated long time delay circuit on thin‐film liquid crystal polymer
Authors: Chen Morgan J. , Zhang Zhaonian , Pham Anh‐Vu H. , Hyman Dan 
Published: February 2009

AbstractA 2‐bit long time delay circuit capable of 0 to 600 ps relative delays has been developed to operate from DC to 10 GHz. This circuit implements an amplitude compensation scheme through use of carefully designed attenuation coefficients on true time delay components that have been developed on a multilayer stack of thin‐film liquid crystal polymer. Minimal insertion losses are achieved by using prototype microelectromechanical system SP4T switches. Insertion losses are measured to be less than 4.3 dB across the band for all delays. Amplitude imbalance is measured to less than ±0.5 dB across the band. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1060–1063, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24231
A simple dual‐band frequency selective surface
Authors: Araújo L. M. , Maniçoba R. H. C. , Campos A. L. P. S. , d'Assunção A. G. 
Published: February 2009

AbstractDesign and experimental investigations are presented for a dual‐band frequency selective surface (FSS) with perfectly conducting rectangular patch elements. The work was developed in two steps. In the first step, two single‐band FSS screens were designed to obtain resonant frequencies at 9.5 GHz and 10.5 GHz, each one with about 1.5 GHz bandwidth. In the second step, these single FSS screens were cascaded and separated by an air gap layer to achieve a dual‐band response. The proposed dual‐band FSS screen is easy to analyze and to fabricate with low cost materials and exhibits a low weight and easy to handle structure. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 942–944, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24236
An enhanced microwave rectifying circuit using HSMS‐282
Authors: He Qijuan , Liu Changjun 
Published: February 2009

AbstractA novel single diode rectifying circuit at 2.45 GHz is presented. An inductor is series‐connected with an HSMS‐282 Schottky diode to enhance the rectification performance. The imaginary part of the complex impedance of the diode is taken into consideration. Simulations and measurements show that the dynamic range of the load is widened with good radio frequency to direct current conversion efficiency (RF‐to‐DC Eff.). A conversion efficiency over 70% is demonstrated in this novel design. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1151–1153, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24237
Miniaturized and harmonics‐rejected slow‐wave branch‐line coupler based on microstrip electromagnetic bandgap element
Authors: Zhang Fei 
Published: February 2009

AbstractThis article presents a planar branch‐line hybrid coupler with an effective technique for harmonic suppression and size reduction. The proposed technique served by a microstrip electromagnetic bandgap element entitled MEBE (compact microstrip resonant cell) is used to suppress the harmonics and reduce the length of a quarter wavelength line when compared with the conventional branch‐line coupler. The planar structure enables an easy circuit implementation in printed circuit boards without any additional process and lumped elements. From the measured results, better than 30 dB suppression for the second harmonic and 18 dB suppression for the third harmonic are obtained while maintaining the characteristics of conventional branch‐line hybrid coupler. It is able to achieve two insertion losses of less than 3.5 dB, the return loss of 18 dB, and isolation of 19 dB at operating frequency. With our improved beeline compact microstrip resonant cell, compact branch‐line coupler occupying areas of 35.86% relative to conventional designs has been realized. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1080–1084, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24241
An integrated packaging antenna‐diplexer module for cellular/SDMB bands with LTCC technology
Authors: Ha Jeung Uk , Chang Kihun , Yoon Young Joong 
Published: February 2009

AbstractThis article presents an integrated packaging antenna‐diplexer module for wireless communication system in the cellular and satellite digital multimedia broadcasting (SDMB) band. Multilayer low temperature cofired ceramic (LTCC) technology with integration capability was used in design and fabrication of the proposed module. To achieve a compact integration, an inverted‐F antenna (IFA) with a meander line and a diplexer composed of low‐pass filter (LPF) and high‐pass filter (HPF) was embedded. The proposed module with dimension of 27.5 × 12.0 × 2.2 mm3operates over a range from 813 to 902 MHz for the cellular band and from 2586 to 2655 MHz for the SDMB band. An isolation level below −25 dB was obtained at each band. The measured gains of the fabricated module are −1.96 and −5.43 dBi, respectively. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1039–1043, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24244
A 5.79‐dB NF, 30‐GHz‐band monolithic LNA with 10 mW power consumption in standard 0.18‐μm CMOS technology
Authors: Chen Chi‐Chen , Lin Yo‐Sheng , Huang Guo‐Wei , Lu Shey‐Shi 
Published: February 2009

AbstractA 30‐GHz (Ka‐band) low‐noise amplifier (LNA) with 10 mW power consumption (PDC) using standard 0.18‐μm CMOS technology was designed and implemented. To achieve sufficient gain, this LNA was composed of three cascade common‐source stages, and a series peaking inductor (Lg3) was added to the input terminal of the third stage to boost the peak gain (S21‐max) from 11.7 (at 28.8 GHz) to 14.5 (at 28 GHz), i.e., 23.9% (simulation). Shunt RC feedback was adopted in the third stage for achieving good output impedance matching. At 30 GHz, this LNA achieved excellent input return loss (S11) of −19.5 dB, output return loss (S22) of −23.8 dB, forward gain (S21) of 11.1 dB, reverse isolation (S12) of −49.2 dB, and noise figure of 5.79 dB. The corresponding gain/PDC was 1.11, which is better than those of the CMOS LNAs around 30 GHz reported in the literature. The measured input‐referred 1‐dB compression point (P1dB‐in) and input third‐order intermodulation point (IIP3) were −10.9 and −2 dBm, respectively. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 933–937, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24250
Triple‐band parallel coupled microstrip bandpass filter with dual coupled length input/output
Authors: Kung Cheng‐Yuan , Chen Yin‐Chung , Yang Cheng‐Fu , Huang Chih‐Yu 
Published: February 2009

AbstractA three‐order triple‐band bandpass filter is proposed to operate at 1.8/3.5/5.2 GHz for DCS, WIMAX, and WLAN applications. Three 1/2λ open‐loop resonators and two novel modified input/output structures parallel coupled are used as the bases. The cascaded resonators are designed for wide bandwidth and high out‐of‐band rejection. The modified input/output structure is used to tune the suppression/improvement of each spurious resonance. The filter is printed on Al2O3ceramic substrate with 0.635 mm in thickness and has the relative dielectric constant 9.4. Because of the high dielectric constant substrate and novel feed in/out structure, the proposed filter with optimized parameters exhibits low insertion loss, high out‐of‐band rejection, wide bandwidth, and simple structure. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 995–997, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24257
A novel compact printed circular antenna for very ultrawideband applications
Authors: Srifi Mohamed Nabil , El Mrabet Otman , Falcone Fransisco , Ayza Mario Sorolla , Essaaidi Mohamed 
Published: February 2009

AbstractIn this article, we present a novel circular disc antenna for current and future ultrawideband (UWB) applications. The proposed antenna has a small size of 30 mm × 35 mm, a simple geometry, and the excitation is launched through a 50‐Ω microstrip feed line. The impedance matching of the proposed antenna is improved by introducing a second microstrip line between the feed line and the circular patch. A prototype of the proposed antenna has been fabricated and its performances are measured. The obtained results show that the proposed antenna operates on UWB frequency range from 2.7 to 28.8 GHz. Measured radiation patterns and simulated gain and radiation efficiency of the proposed antenna are presented and discussed. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1130–1133, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24261
Analysis of a radial infusion model for in‐plane permeability measurements of fiber reinforcement in composite materials
Authors: Mekic Sait , Akhatov Iskander S. , Ulven Chad A. 
Published: February 2009

AbstractThe principal components of in‐plane permeability of fiber reinforcement during resin infusion can be determined by unidirectional or by radial flow experiments. Using unidirectional flow, two separate experiments are required to determine both components if the directions of principal axis are known. The main drawback of this method is related to the edge flow that may significantly affect the accuracy of measurements. In radial flow, both principal components can be determined by performing one experiment when the directions of principal axis are known. However, developed models that apply to this method require iterative procedures and are highly sensitive to the radius of the injection port. Measurements of the flow front displacement have to be taken when the wetted area becomes large enough in comparison with the size of the inlet gate. This analysis is based on a quasi‐steady radial infusion model developed by Adams et al., Int. J. Multiphase Flow, 14, 203 (1988), which is used for calculation of the principal components of in‐plane permeability. It is shown that the anisotropy coefficient and consequent permeability may be evaluated at any stage of the flow front displacement. This implies that the pressure difference does not necessarily need to be constant during the experiment, as usually required for most previous models. Asymptotic analysis for very small and very large flow front displacements is also conducted and comparison with point source algorithms is provided. Three accurate and relatively simple algorithms that do not require iterative procedures for evaluation of in‐plane components of permeability are proposed. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers
Changes in children's peer interactions following a natural disaster: How predisaster bullying and victimization rates changed following Hurricane Katrina
Authors: Terranova Andrew M. , Boxer Paul , Morris Amanda Sheffield 
Published: February 2009

AbstractYouth exposed to disasters experience stress and adjustment difficulties, which likely influence their interactions with peers. In this study, we examined changes in bullying and peer victimization in two cohorts of children. Youth from an area affected by Hurricane Katrina were assessed pre‐ and postdisaster (n = 96, mean [M] = 10.9 years old, 53% female), and a comparison group from a nearby area was assessed over the same time interval 1 year prior (n = 120, M = 10.2 years old, 52% female). Within the hurricane group, relations between symptoms of post‐traumatic stress disorder (PTSD) with bullying and victimization also were examined. Following the hurricane, the hurricane group reported increased relational and overt bullying relative to the nonhurricane group, and PTSD symptoms predicted increased victimization. Thus, school personnel should be vigilant and prepared to respond to increased bullying following disasters and for increased victimization in youth experiencing PTSD symptoms. © 2009 Wiley Periodicals, Inc.
Social preference choices in late elementary school: Within and across group nominations
Authors: Farmer Thomas W. , Leung Man‐Chi , Keagy Kristen , Boudah Daniel J. , Akos Patrick , McDonough Erin , Hall Cristin M. 
Published: February 2009

AbstractThis study examined the social preference nominations (i.e., “liked most” and “liked least”) in relation to peer group and classroom social dynamics in a sample of 622 fifth graders from 11 schools in a southeastern state. Liked most and liked least nominations were given to a small concentration of students within classrooms. The top five nominees for liked most and liked least tended to be in peer groups and associated with at least one classmate who shared their position as a top nominee. The majority of liked most nominations in a classroom were made toward members inside the nominator's group, whereas the majority of liked least nominations were made toward peers outside one's group. Students in the same peer group were more likely to nominate the same peers as liked most than were students who did not affiliate together. In contrast, the concordance for liked least nominations was moderate at both the peer‐group and classroom level. Implications for school‐based social interventions are discussed. © 2009 Wiley Periodicals, Inc.
Novel side‐chain naphthalimide polyphenylacetylene as a ratiometric fluorescent chemosensor for fluoride ion
Authors: Qu Yi , Hua Jianli , Jiang Yihua , Tian He 
Published: February 2009

AbstractNovel polyphenylacetylene (P1) containing naphthalimides units in the side chain was designed and synthesized. The structure and properties of the polymer were characterized and evaluated by IR, NMR, UV, and PL. The measurements of sensing behavior to various halide anions, that is, F−, Cl−, Br−, and I−, reveal that the polymer is a ratiometric fluorescent chemosensors for fluoride ion. The polymer sensor shows spectral shifts and intensity changes in the presence of fluoride, in a wavelength‐ratiometric and ‐colorimetric manner, which can detect fluoride concentrations in range of 10–100 μM at visible wavelengths. The obvious colorless‐to‐yellow color change and blue‐to‐orange emission color change on the addition of fluoride ion are easily observed by naked eyes. It provides a feasible way to construct a ratiometric fluorescent chemosensors for fluoride ion. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1544–1552, 2009
Synthesis and characterization of fluorene‐based copolymers containing siloxane or distilbene moieties on their main chain
Authors: Cho Hoon‐Je , Park Moo‐Jin , Hwang Do‐Hoon , Ahn Taek , Hong Ji‐Won , Lee Jonghee , Cho Nam Sung , Shim Hong‐Ku 
Published: February 2009

AbstractTwo novel types of polyfluorene copolymers containing siloxane linkages or distilbene moieties on their main‐chains were synthesized by Ni(0)‐mediated Yamamoto coupling polymerization. These polymers, designated P2Silo05, P2Silo15, PF‐P02, and PF‐P05 were prepared by copolymerization between 2,7‐dibromo‐9,9′‐dihexylfluorene and bis(bromobenzene)‐terminated disiloxane monomer (for P2Silo05 and P2Silo15) or dibromodistilbene monomer (for PF‐P02 and PF‐P05). All of the polymers were highly soluble in common organic solvents such as chloroform, toluene, and p‐xylene. The glass transition temperatures of the polymers were between 92 and 113 °C, and the decomposition temperatures for a 5% weight loss (Td) were above 420 °C for all of the polymers, demonstrating high thermal stability. The molecular weight (Mw) of the polymers ranged from 4.2 × 104 to 8.8 × 104. The blue shift of the maximum in the UV‐visible absorption was greater in polymers with a higher molar percentage of siloxane linkages or distilbene moieties than in homo poly (dihexylfluorene) (PDHF). However, the photoluminescence spectra of the polymers were similar to those of PDHF in terms of the onsets and patterns. Single‐layer light‐emitting diodes were fabricated with a configuration of ITO/PEDOT:PSS/polymers/Ca/Al. The maximum electroluminescence emission wavelengths of the polymers were 425–450 nm, corresponding to pure blue light. The CIE co‐ordinates of the polyfluorenes containing siloxane linkages or distilbene moieties ranged from (0.21, 0.21) to (0.17, 0.10), indicating deeper blue light than that of PDHF {CIE co‐ordinates of (0.25, 0.29)}, with P2Silo15 giving the deepest blue‐light {CIE co‐ordinates of (0.17, 0.10)}. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1595–1608, 2009
Synthesis of copolyfluorenes containing green chromophores based on triphenylamine unit and their application in light‐emitting diodes
Authors: Hsieh Bar‐Yuan , Chen Yun 
Published: February 2009

AbstractTwo series of new copolyfluorenes (PFTP, PFTT) were prepared by the Suzuki coupling reaction from two green‐emitting dibromo monomers (TP‐Br, TT‐Br) based on triphenylamine unit to be applied in white light electroluminescent devices. They were characterized by molecular weight determination, elemental analysis, DSC, TGA, absorption and photoluminescence spectra, and cyclic voltammetry. The estimated actual contents of the TP and TT chromophores were lower than 7.8 mol % and 1.9 mol % for PFTP and PFTT, respectively. In film state both copolyfluorenes showed photoluminescence at 400–470 and 470–600 nm originated from fluorene segments and the chromophores, respectively, due to incomplete energy transfer. Light‐emitting diodes with a structure of ITO/PEDOT:PSS/copolymer/Ca(50 nm)/Al(100 nm) showed major emission at 493–525 nm, plus minor emission at 400–470 nm when chromophore contents were low. The maximum brightness and maximum current efficiency of PFTP2 device were 8370 cd/m2 and 1.47 cd/A, whereas those of PFTT1 device were 9440 cd/m2 and 1.77 cd/A, respectively. Tri‐wavelength white‐light emission was realized through blending PFTT1 with poly(9,9‐dihexylfluorene) and a red‐emitting iridium complex, in which the maximum brightness and CIE coordinates were 6880 cd/m2 and (0.31, 0.33), respectively. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1553–1566, 2009
A green fluorescent protein screen for identification of well‐expressed membrane proteins from a cohort of extremophilic organisms
Authors: Hammon Justus , Palanivelu Dinesh V. , Chen Joy , Patel Chintan , Minor Daniel L. 
Published: February 2009

AbstractGreen fluorescent protein (GFP) fusion proteins provide a potentially facile tool for identification of well expressed, properly behaved membrane proteins for biochemical and structural study. Here, we present a GFP‐expression survey of >300 membrane proteins from 18 bacterial and archaeal extremophiles, organisms expected to be rich sources of membrane proteins having robust biophysical properties. We find that GFP‐fusion fluorescence intensity is an excellent indicator of over‐expression potential. By employing a follow‐up optimization protocol using a suite of non‐GFP constructs and different expression temperatures, we obtain 0.5–15 mg L−1 expression levels for 90% of the tested candidate proteins that pass the GFP screen. Evaluation of the results suggests that certain organisms may serve as better sources of well‐expressed membrane proteins than others, that the degree to which codon usage matches the expression host is uncorrelated with success rate, and that the combination of GFP screening and expression optimization is essential for producing biochemically tractable quantities of material.
Ion‐specific modulation of protein interactions: Anion‐induced, reversible oligomerization of a fusion protein
Authors: Gokarn Yatin R. , Fesinmeyer R. Matthew , Saluja Atul , Cao Shawn , Dankberg Jane , Goetze Andrew , Jr. Richard L. Remmele , Narhi Linda O. , Brems David N. 
Published: February 2009

AbstractIons can significantly modulate the solution interactions of proteins. We aim to demonstrate that the salt‐dependent reversible heptamerization of a fusion protein called peptibody A or PbA is governed by anion‐specific interactions with key arginyl and lysyl residues on its peptide arms. Peptibody A, an E. coli expressed, basic (pI = 8.8), homodimer (65.2 kDa), consisted of an IgG1‐Fc with two, C‐terminal peptide arms linked via penta‐glycine linkers. Each peptide arm was composed of two, tandem, active sequences (SEYQGLPPQGWK) separated by a spacer (GSGSATGGSGGGASSGSGSATG). PbA was monomeric in 10 mM acetate, pH 5.0 but exhibited reversible self‐association upon salt addition. The sedimentation coefficient (sw) and hydrodynamic diameter (DH) versus PbA concentration isotherms in the presence of 140 mM NaCl (A5N) displayed sharp increases in sw and DH, reaching plateau values of 9 s and 16 nm by 10 mg/mL PbA. The DH and sedimentation equilibrium data in the plateau region (>12 mg/mL) indicated the oligomeric ensemble to be monodisperse (PdI = 0.05) with a z‐average molecular weight (Mz) of 433 kDa (stoichiometry = 7). There was no evidence of reversible self‐association for an IgG1‐Fc molecule in A5N by itself or in a mixture containing fluorescently labeled IgG1‐Fc and PbA, indicative of PbA self‐assembly being mediated through its peptide arms. Self‐association increased with pH, NaCl concentration, and anion size (I− > Br− > Cl− > F−) but could be inhibited using soluble Trp‐, Phe‐, and Leu‐amide salts (Trp > Phe > Leu). We propose that in the presence of salt (i) anion binding renders PbA self‐association competent by neutralizing the peptidyl arginyl and lysyl amines, (ii) self‐association occurs via aromatic and hydrophobic interactions between the ..xx..xxx..xx.. motifs, and (iii) at >10 mg/mL, PbA predominantly exists as heptameric clusters.
High tolerance to simultaneous active‐site mutations in TEM‐1 β‐lactamase: Distinct mutational paths provide more generalized β‐lactam recognition
Authors: De Wals Pierre‐Yves , Doucet Nicolas , Pelletier Joelle N. 
Published: February 2009

AbstractThe diversity in substrate recognition spectra exhibited by various β‐lactamases can result from one or a few mutations in the active‐site area. Using Escherichia coli TEM‐1 β‐lactamase as a template that efficiently hydrolyses penicillins, we performed site‐saturation mutagenesis simultaneously on two opposite faces of the active‐site cavity. Residues 104 and 105 as well as 238, 240, and 244 were targeted to verify their combinatorial effects on substrate specificity and enzyme activity and to probe for cooperativity between these residues. Selection for hydrolysis of an extended‐spectrum cephalosporin, cefotaxime (CTX), led to the identification of a variety of novel mutational combinations. In vivo survival assays and in vitro characterization demonstrated a general tendency toward increased CTX and decreased penicillin resistance. Although selection was undertaken with CTX, productive binding (KM) was improved for all substrates tested, including benzylpenicillin for which catalytic turnover (kcat) was reduced. This indicates broadened substrate specificity, resulting in more generalized (or less specialized) variants. In most variants, the G238S mutation largely accounted for the observed properties, with additional mutations acting in an additive fashion to enhance these properties. However, the most efficient variant did not harbor the mutation G238S but combined two neighboring mutations that acted synergistically, also providing a catalytic generalization. Our exploration of concurrent mutations illustrates the high tolerance of the TEM‐1 active site to multiple simultaneous mutations and reveals two distinct mutational paths to substrate spectrum diversification.