bluuebunny/crossref_metadata_2025 huggingface dataset:
G protein regulator 1 (GPR‐1) localizes to cortical sites of artificial mechanical indentation in Caenorhabditis elegans zygotes
Authors: Bringmann Henrik
Published: August 2012

Cytokinesis and spindle positioning require the cortical force regulator G Protein Regulator 1/2 (GPR‐1/2). GPR‐1/2 is thought to localize to sites of cortical force generation. Does GPR‐1/2 also act as a sensor for mechanical stimulation? I mechanically stimulated the cortex by indenting it with a glass needle and observed the cortical localization of a YFP::GPR‐1 transgene. I found that cortical YFP::GPR‐1 accumulated at the site of mechanical indentation. This phenomenon occurred on most of the cortical areas except the site of prospective cytokinesis furrow formation. This result suggests that GPR‐1/2 can sense mechanical properties of the cortex, which may be important for GPR‐1/2 function regulating spindle positioning and cytokinesis. © 2012 Wiley Periodicals, Inc
Nucleophilic Addition Reactions of the Nitroprusside Ion – The Case of O‐Methylhydroxylamine
Authors: Gutiérrez María M. , Olabe José A. , Amorebieta Valentín T.
Published: August 2012

The kinetics of the reaction between aqueous solutions of [Fe(CN)5NO]2– and NH2OCH3 has been studied by means of UV/Vis spectroscopy and complementary solution techniques, FTIR/ATR spectroscopy, mass spectrometry, and isotopic labeling ([Fe(CN)515NO]2–), in the pH range 6.0–9.3, I = 1 M (NaCl). The main products were nitrous oxide (N15NO), CH3OH, and [FeII(CN)5H2O]3–, characterized as the [FeII(CN)5(pyCONH2)]3– complex (pyCONH2 = isonicotinamide). In excess NH2OCH3, the kinetic runs indicated pseudo‐first‐order behavior, with corresponding rate constants, kobs [s–1], that correlated linearly with the concentration of NH2OCH3. The rate law is: R = kexp[Fe(CN)5NO2–][NH2OCH3], with kexp = (4.1 ± 0.4) × 10–4 M–1 s–1 at 25 ± 0.2 °C, ΔH# = 27 ± 1 kJ mol–1, and ΔS# = –220 ± 5 J K–1 mol–1, at pH 7.1. The value of kexp is much lower than that for similar addition reactions of NH2OH and of the N‐substituted methyl derivative. In addition, the latter reactions exhibit a third‐order rate law with a linear dependence of R on the concentration of OH–. The reaction profile has been modeled by density functional theoretical methodologies, providing mechanistic evidence on the different reaction steps, namely, the adduct formation and subsequent decomposition processes, with valuable comparisons with the reactivity of other nucleophiles with [Fe(CN)5NO]2–.
Solvolysis of a Series of Cisplatin‐Like Complexes – Comparison between DNA‐Biosensor and Conductivity Data
Authors: Platts James A. , Ravera Mauro , Gabano Elisabetta , Sardi Manuele , Bianco Sabrina , Osella Domenico
Published: August 2012

The kinetics of solvolysis in pure dimethyl sulfoxide (DMSO) and water/DMSO or water/dimethylformamide (DMF) mixtures of a series of variously N‐methylated ethylenediamine (en*) derivatives, cis‐[PtCl2(en*)], were studied by using an electrochemical biosensor consisting of DNA immobilized on the surface of screen‐printed electrodes, by conductivity measurements, and by multinuclear NMR spectroscopy and ESI‐MS techniques. The pattern of the kinetics was found to have significant differences between solvents, especially between the strongly coordinating DMSO and the weakly coordinating DMF co‐solvent, employed to increase the solubility of the complexes under study. In particular, cisplatin and cis‐[PtCl2(en*)] show rapid solvolysis in the former but significantly slower in the latter, which indicates that the affinity of the Pt core for the S‐donor atoms of DMSO overcomes the effect of its steric hindrance. In order to probe these reactions in more detail, density functional theory (DFT) calculations of activation barriers to solvolysis by both pure DMSO and H2O were performed.
Direct C–H Alkylation of Naphthoquinones with Amino Acids Through a Revisited Kochi–Anderson Radical Decarboxylation: Trends in Reactivity and Applications
Authors: Naturale Guillaume , Lamblin Marc , Commandeur Claude , Felpin François‐Xavier , Dessolin Jean
Published: August 2012

In our ongoing research program into the discovery of new anticancer drugs , we were interested in the preparation of naphthoquinone scaffolds bearing aminoalkyl side‐chains. Following this aim, we revisited the Kochi–Anderson radical decarboxylation of amino acids in order to set up a versatile route to the direct functionalization of naphthoquinones. The best reaction conditions were applied to a selected series of compounds in a systematic methodological study which allowed us to establish important trends in reactivity. We found that α‐substituted β‐amino acids were the most suitable substrates for the radical addition. In contrast, α‐amino acids gave modest results. The influence of the amine protecting groups on the reaction outcome has also been studied. This practical procedure allows the introduction of various unsymmetrical moieties, including orthogonally protected linear aminoalkyl chains or chiral dipeptidic chains, and opens the door to a wide scope of easily accessible chemical diversity.
Electrochemical Investigation for Cu2+ Oscillatory Phenomena at the Liquid/Liquid Interface with a Specific Adsorption of Ion Pair Model
Authors: Zhang Yijun , Bu Caihong , Wang Yongcheng , Wang Zhihua , Lu Xiaoquan , Liu Xiuhui
Published: August 2012

In this paper, a novel current oscillatory phenomenon for Cu2+ at the water/1,2‐dichloroethane interface is reported with cyclic voltammetry and potential‐step chronoamperometry. The small irregular current spikes were only observed near the site of the oxidation peak of CuCl2− and were mainly related to the Cu2+concentration in the aqueous phase. Our experimental results demonstrated that the current oscillation is caused by specific adsorption of ion pairs at the W/DCE interface between Cu2+ in the aqueous phase and TPB− in the organic phase. Therefore, a specific adsorption of ion pair model has been formulated for the current oscillation at the liquid/liquid interface. The DFT calculation method was used to explain the mechanism of ion pair formation. The calculation results suggested that the TPB−Cu2+TPB− ion pair has the lowest‐energy state, thus providing qualitative support for the ion pair model. A probable mechanism for the observed current oscillation was also discussed in this paper. At the same time, a spectrophotometric experiment was performed to evidence a strong attractive interaction between Cu2+ and TPB−.
Detection of Cadmium and Copper Cations Using Amorphous Nitrogenated Carbon Thin Film Electrodes
Authors: Seck Serigne Massamba , Charvet Stéphane , Fall Modou , Baudrin Emmanuel , Lejeune Michaël , Benlahsen Mohammed
Published: August 2012

Nitrogenous amorphous carbon (a‐CNx) thin films were deposited by radio‐frequency cathodic magnetron sputtering (13.56 MHz) on polished and etched titanium disks. While these films are cheaper to prepare than commonly reported carbon‐based electrodes, the usable electrochemical window in aqueous solution is within the same range and spans from −1.5 to +1.8 V vs. SCE. The electrochemical reactivity was tested using the ferri‐ferrocyanide redox couple as a function of the thin films preparation parameters. The obtained electrochemical properties allow the use of these a‐CNx thin films for stripping electroanalysis of cations in water, minimizing potential solvent reactivity. Cadmium and copper were used to test these detection abilities. Better analytical properties (notably sensitivity and linearity) were obtained as compared to a commercial boron doped diamond electrode. Preliminary competition/interaction experiments for these two cations were performed.
Stormwater contaminant loading following southern California wildfires
Authors: Stein Eric D. , Brown Jeffrey S. , Hogue Terri S. , Burke Megan P. , Kinoshita Alicia
Published: August 2012

Contaminant loading associated with stormwater runoff from recently burned areas is poorly understood, despite the fact that it has the potential to affect downstream water quality. The goal of the present study is to assess regional patterns of runoff and contaminant loading from wildfires in urban fringe areas of southern California. Postfire stormwater runoff was sampled from five wildfires that each burned between 115 and 658 km2 of natural open space between 2003 and 2009. Between two and five storm events were sampled per site over the first one to two years following the fires for basic constituents, metals, nutrients, total suspended solids, and polycyclic aromatic hydrocarbons (PAHs). Results were compared to data from 16 unburned natural areas and six developed sites. Mean copper, lead, and zinc flux (kg/km2) were between 112- and 736-fold higher from burned catchments and total phosphorus was up to 921-fold higher compared to unburned natural areas. Polycyclic aromatic hydrocarbon flux was four times greater from burned areas than from adjacent urban areas. Ash fallout on nearby unburned watersheds also resulted in a threefold increase in metals and PAHs. Attenuation of elevated concentration and flux values appears to be driven mainly by rainfall magnitude. Contaminant loading from burned landscapes has the potential to be a substantial contribution to the total annual load to downstream areas in the first several years following fires. Environ. Toxicol. Chem. 2012; 31: 2625–2638. © 2012 SETAC
Net trophic transfer efficiencies of polychlorinated biphenyl congeners to lake trout (Salvelinus namaycush) from its prey
Authors: Madenjian Charles P. , David Solomon R. , Rediske Richard R. , O'Keefe James P.
Published: August 2012

Lake trout (Salvelinus namaycush) were fed bloater (Coregonus hoyi) in eight laboratory tanks over a 135-d experiment. At the start of the experiment, four to nine fish in each tank were sacrificed, and the concentrations of 75 polychlorinated biphenyl (PCB) congeners within these fish were determined. Polychlorinated biphenyl congener concentrations were also determined in the 10 lake trout remaining in each of the eight tanks at the end of the experiment as well as in the bloater fed to the lake trout. Each lake trout was weighed at the start and the end of the experiment, and the amount of food eaten by the lake trout was recorded. Using these measurements, net trophic transfer efficiency (γ) from the bloater to the lake trout in each of the eight tanks was calculated for each of the 75 congeners. Results showed that γ did not vary significantly with the degree of chlorination of the PCB congeners, and γ averaged 0.66 across all congeners. However, γ did show a slight, but significant, decrease as log KOW increased from 6.0 to 8.2. Activity level of the lake trout did not have a significant effect on γ. Environ. Toxicol. Chem. 2012; 31: 2821–2827. © 2012 SETAC
Neuropsychiatric symptoms, apolipoprotein E gene, and risk of progression to cognitive impairment, no dementia and dementia: the Aging, Demographics, and Memory Study (ADAMS)
Authors: Beaudreau Sherry A. , Kaci Fairchild J. , Spira Adam P. , Lazzeroni Laura C. , O'Hara Ruth
Published: August 2012

Objective

To examine the relationship of neuropsychiatric symptoms and apolipoprotein E (APOE) ε4 allele status to dementia at baseline and progression to dementia in older adults with and without cognitive impairment, no dementia (CIND).

Methods

Adults (n = 856) 71 years and older (mean age = 79.15 years), 12.8% ethnic minority and 60.6% women, completed neuropsychological tests and APOE genotyping, and a proxy informant completed the Neuropsychiatric Inventory.

Results

After adjusting for age and education, neuropsychiatric symptoms and APOE ε4 were independently associated with CIND and dementia status at baseline (compared with cognitively normal). Further, neuropsychiatric symptoms predicted progression to dementia at 16‐ to 18‐month follow‐up among participants with CIND at baseline; the presence of these symptoms decreased the risk of progression from normal to CIND or dementia at 36 to 48 months.

Conclusion

Findings provide cross‐sectional and longitudinal support for the role of neuropsychiatric symptoms in the prediction of cognitive impairment, particularly dementia. APOE ε4, although important, may be a less robust predictor. This investigation highlights the importance of behavioral symptoms, such as neuropsychiatric symptom status or frequency/severity, as predictors of future cognitive decline. Copyright © 2012 John Wiley & Sons, Ltd.
High prevalence of confirmed, but also of potential and believed, neuropathic pain in pain clinics
Authors: Pérez C. , Ribera M.V. , Gálvez R. , Micó J.A. , Barutell C. , Failde I. , Sánchez‐Magro I. , Stern A.
Published: August 2012

Background and aims

Epidemiological data about neuropathic pain are still scarce. A national survey, based on neurologic clinical diagnosis, was performed to determine its prevalence among patients attending pain clinics.

Methods

An epidemiological cross‐sectional study involving pain clinics across all regions in Spain was carried out. Pain specialists evaluated the medical files and the clinical condition of patients attending their practices systematically during 1 day. They used the revised definition and grading system proposed in 2008 to decide whether a given patient had definite (i.e., confirmed), probable (potential) or possible (believed) neuropathic pain. Also, they provided a diagnostic label for neuropathic pain conditions and appraised treatment adequacy.

Results

In a single day, 178 pain specialists provided data from 2173 patients. Definite, probable and possible neuropathic pain was cited in 639 (29.4%), 304 (14.0%) and 97 (4.5%) patients, respectively. Almost two‐thirds of these were women. A diagnostic label of primary pure central and/or peripheral neuropathic pain was cited in 344 (15.8%) patients. The most common diagnostic label (568 patients) was low back pain or sciatica causing mixed neuropathic pain. Definite neuropathic pain diagnosis was less likely in patients with mixed pain conditions and in women derived from primary care. Co‐morbid depressive or anxiety symptoms were usual.

Conclusions

Definite (confirmed) neuropathic pain alone was as prevalent as neuropathic pain ascertained with screening questionnaires in prior recent European studies. The clinical relevance of the surplus of patients with potential and believed neuropathic pain ascertained by clinicians is uncertain.
ERα signaling regulates MMP3 expression to induce FasL cleavage and osteoclast apoptosis
Authors: Garcia Alejandro J , Tom Colton , Guemes Miriam , Polanco Gloria , Mayorga Maria E , Wend Korinna , Miranda-Carboni Gustavo A , Krum Susan A
Published: August 2012

The benefits of estrogens on bone health are well established; how estrogens signal to regulate bone formation and resorption is less well understood. We show here that 17β-estradiol (E2)-induced apoptosis of bone-resorbing osteoclasts is mediated by cleavage and solubilization of osteoblast-expressed Fas ligand (FasL). U2OS-ERα osteoblast-like cells expressing an EGFP-tagged FasL at the C-terminus showed decreased fluorescence after E2 treatment, indicative of a cleavage event. Treatment of U2OS-ERα cultures with a specific MMP3 inhibitor in the presence of E2 blocked FasL cleavage and showed an increase in the number of EGFP-FasL+ cells. siRNA experiments successfully knocked down MMP3 expression and restored full-length FasL to basal levels. E2 treatment of both human and murine primary osteoblasts showed upregulation of MMP3 mRNA expression, and calvarial organ cultures showed increased expression of MMP3 protein and colocalization with the osteoblast-specific RUNX2 after E2 treatment. In addition, osteoblast cell cultures derived from ERαKO mice showed decreased expression of MMP3 but not MMP7 and ADAM10, two known FasL proteases, demonstrating that ERα signaling regulates MMP3. Also, conditioned media of E2-treated calvarial osteoblasts showed an approximate sixfold increase in the concentration of soluble FasL, indicating extensive cleavage, and soluble FasL concentrations were reduced in the presence of a specific MMP3 inhibitor. Finally, to show the role of soluble FasL in osteoclast apoptosis, human osteoclasts were cocultured with MC3T3 osteoblasts. Both a specific MMP3 inhibitor and an MMP inhibitor cocktail preserved osteoclast differentiation and survival in the presence of E2 and demonstrate the necessity of MMP3 for E2-induced osteoclast apoptosis. These experiments further define the molecular mechanism of estrogen's bone-protective effects by inducing osteoclast apoptosis through upregulation of MMP3 and FasL cleavage. © 2013 American Society for Bone and Mineral Research
Functional arterial spin labeling: Optimal sequence duration for motor activation mapping in clinical practice
Authors: Raoult Hélène , Ferré Jean–Christophe , Petr Jan , Bannier Elise , Stamm Aymeric , Barillot Christian , Gauvrit Jean‐Yves
Published: August 2012

Purpose:

To determine the minimal optimal functional arterial spin labeling (fASL) sequence duration allowing steady and reproducible motor activation mapping.

Materials and Methods:

Three magnetic resonance imaging (MRI) sessions including fASL and blood oxygenation level‐dependent (BOLD) functional MRI (fMRI) sequences were performed on 12 healthy subjects at 3T with a 32‐channel coil. The raw 7‐minute fASL sequence was truncated to obtain six fASL sequences with durations ranging from 1–6 minutes. All the resulting fASL activations were compared between themselves and with both the 7‐minute fASL and BOLD activations. Quantitative parameters assessed activation location (activated volume, barycenter, and distance between barycenters), activation quantification (activation‐related cerebral blood flow), and intraindividual reproducibility across fMRI sessions. The statistical analysis was based on analysis of variance (ANOVA) and Tukey's multiple comparisons.

Results:

Four‐minute fASL achieved steady location and quantification of activation with the activated volume corresponding to 81% of the 7‐minute fASL volume and a barycenter located 1.2 mm from the 7‐minute fASL barycenter and 3.0 mm from the BOLD fMRI barycenter. Four‐minute fASL reproducibility was high and statistically equivalent to 7‐minute values.

Conclusion:

A 4‐minute fASL sequence is thus a reliable tool for motor activation mapping and suitable for use in clinical practice. J. Magn. Reson. Imaging 2012; 36:1435–1444. © 2012 Wiley Periodicals, Inc.
Automating network meta‐analysis
Authors: van Valkenhoef Gert , Lu Guobing , de Brock Bert , Hillege Hans , Ades A. E. , Welton Nicky J.
Published: August 2012

Mixed treatment comparison (MTC) (also called network meta‐analysis) is an extension of traditional meta‐analysis to allow the simultaneous pooling of data from clinical trials comparing more than two treatment options. Typically, MTCs are performed using general‐purpose Markov chain Monte Carlo software such as WinBUGS, requiring a model and data to be specified using a specific syntax. It would be preferable if, for the most common cases, both could be derived from a well‐structured data file that can be easily checked for errors. Automation is particularly valuable for simulation studies in which the large number of MTCs that have to be estimated may preclude manual model specification and analysis. Moreover, automated model generation raises issues that provide additional insight into the nature of MTC. We present a method for the automated generation of Bayesian homogeneous variance random effects consistency models, including the choice of basic parameters and trial baselines, priors, and starting values for the Markov chain(s). We validate our method against the results of five published MTCs. The method is implemented in freely available open source software. This means that performing an MTC no longer requires manually writing a statistical model. This reduces time and effort, and facilitates error checking of the dataset. Copyright © 2012 John Wiley & Sons, Ltd.
Characterization of Pressure Effects on the Cohesive Properties and Structure of Hexane and Polyethylene Using Molecular Dynamics Simulations
Authors: Shahamat Moeed , Rey Alejandro D.
Published: August 2012

Molecular dynamics (MD) simulations using the OPLS‐AA force field are conducted to compute pressure‐ and molecular‐weight‐dependence of Hildebrand's solubility parameters of hexane and high‐density polyethylene (HDPE) at high pressures. The pressure dependence investigation also captures density data computed at high temperature and for external pressures ranging from 100 to 3000 bar. The effect of electrostatic potential energy contribution to cohesive energy and density is investigated and it is shown that the solubility parameter increases monotonically with increasing external pressure for both molecular mechanical models with and without electrostatic terms. Analysis of the pair distribution function is carried out versus pressure together with the influence of electrostatic energy contribution reflecting structural change of the condensed phase.

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Iron‐regulated metabolites produced by Pseudomonas fluorescens WCS374r are not required for eliciting induced systemic resistance against Pseudomonas syringae pv. tomato in Arabidopsis
Authors: Djavaheri Mohammad , Mercado‐Blanco Jesús , Versluis C. , Meyer J.‐M. , Van Loon L. C. , Bakker Peter A. H. M.
Published: August 2012

The plant growth‐promoting rhizobacterium Pseudomonas fluorescens WCS374r produces several iron‐regulated metabolites, including the fluorescent siderophore pseudobactin (Psb374), salicylic acid (SA), and pseudomonine (Psm), a siderophore that contains a SA moiety. After purification of Psb374 from culture supernatant of WCS374r, its structure was determined following isoelectrofocusing and tandem mass spectrometry, and found to be identical to the fluorescent siderophore produced by P. fluorescens ATCC 13525. To study the role of SA and Psm production in colonization of Arabidopsis thaliana roots and in induced systemic resistance (ISR) against Pseudomonas syringae pv. tomato (Pst) by strain WCS374r, mutants disrupted in the production of these metabolites were obtained by homologous recombination. These mutants were further subjected to transposon Tn5 mutagenesis to generate mutants also deficient in Psb374 production. The mutants behaved similar to the wild type in both their Arabidopsis rhizosphere‐colonizing capacity and their ability to elicit ISR against Pst. We conclude that Psb374, SA, and Psm production by P. fluorescens WCS374r are not required for eliciting ISR in Arabidopsis.
Ferrite loaded UHF sleeve monopole integrated with a GPS patch antenna for a handset
Authors: Rama Rao B. , Elloian Jeffrey M. , Rosario E.N. , Davis R. J.
Published: August 2012

This article describes the design of a compact ferrite loaded UHF sleeve monopole antenna covering 225–450 MHz that is colocated with GPS annular ring microstrip antennas on top of a handset. This antenna provides both communications and navigational capabilities to the user and is intended for military and commercial applications. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2513–2516, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27102
Reduction of cross‐polarization in offset reflectarrays using two layers of varying‐sized patches
Authors: Tienda C. , Encinar Jose A. , Barba M. , Arrebola M.
Published: August 2012

An offset‐fed reflectarray demonstrator with reduced cross‐polarization has been designed, manufactured, and tested.It is demonstrated that the cross‐polarization is significantly reduced by using two layers of varying‐sized patches and adjusting the patch dimensions not only to shape the beam in dual‐linear polarization but also to produce a cancellation of the cross‐polarized reflected field in those zones in which the maximum cross‐polarization is produced. The proposed technique provides a reduction better than 5 dB in the cross‐polarization for both linear polarizations. The measured radiation patterns are in good agreement with the theoretical predictions, and show a cross‐polar discrimination better than 30 dB in the 12.97–14.25 GHz frequency band. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2449–2454, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27106
Sensitivity and stability characterization of linear cavity erbium‐doped fiber laser for pressure measurement
Authors: Mohd Idris Sumayyah , Al‐Taha Mohammed Rafid Haleem , Ismail Aiman , Abdullah Fairuz , Jamaludin Md Zaini , Al‐Mansoori Mohammed Hayder
Published: August 2012

This article reports a linear cavity Erbium‐doped fiber (EDF) laser for pressure measurement.The fiber laser structure comprises an EDF amplifier, a circulator, an optical coupler, and a fiber Bragg grating (FBG) which is fitted to the shock tube where the pressure is applied. The FBG acts simultaneously as a lasing wavelength selecting component as well as a pressure sensor. The novelty of this sensor lies in its enhanced characteristic with 0.122 nm/bar sensitivity and very good stability with an average power fluctuation of 0.0025 dB over a period of 60 min. Preliminary results have proven to show that the fiber laser sensor is expected to be an attractive choice for long‐distance pressure monitoring. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2447–2449, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27107
Fast optimization of microwave absorbers
Authors: Kubytskyi Viacheslav , Sapoval Bernard , Dun Gwenaël , Rosnarho Jean‐François
Published: August 2012

We address the question of the optimization of the performance of microwave absorbers. Our approach first use an optimization algorithm applied to a one‐dimensional (1D) homogenized equivalent structure. The optimization yields a refractive index profile which is then used to build a 3D curved pyramidal structure. The validity of this approach is then verified through full‐wave 3D numerical simulations. We address two type of questions: optimization of the shape for a given refractive index and optimization of material properties. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2472–2477, 2012; this online at wileyonlinelibrary.com. DOI 10.1002/mop.27108
X‐Band GaAs mmic high power amplifier for transmitter space module
Authors: Giofre Rocco , Colantonio Paolo , Giannini Franco , Piazzon Luca
Published: August 2012

In this letter, the design, realization, and test of an X‐band GaAs microwave monolithic integrated circuit high power amplifier (HPA) are reported.The HPA is designed in a two stage configuration to fully match a 50 Ω input and output impedance. Experimental results show that the HPA reaches an output power higher than 38 dBm with a gain higher than 17 dB and a ripple lower than 0.5 dB from 9 to 10.2 GHz frequency range. The power added efficiency is around 40%. The good level of performance and the low sensitivity to the environment temperature make this amplifier an excellent candidate for X band applications in phased array active antennas. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2633–2635, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27109
Balanced wideband BPF design using stub‐loaded multimode resonator for MB‐OFDM application
Authors: Lee Ching‐Her , Chang Tsung‐Han , Hsu Chung‐I G. , Chang Jhih‐Hong
Published: August 2012

In this article, a new balanced wideband bandpass filter (BPF) is designed using a stub‐loaded multimode resonator (SLMMR) with tightly coupled feeding lines. The wideband response is achieved by designing the first three differential resonant modes of the SLMMR to locate evenly in the designated passband. Good common‐mode (CM) suppression over the passband is obtained by positioning the transmission zero produced by one half of the low‐impedance section (which serves as a shunt open‐circuited stub while the BPF is in CM operation) of the SLMMR close to the in‐band common modes. A prototype of the proposed BPF is fabricated and measured; the measured (simulated) minimum differential‐mode insertion loss (IL) is 0.7 (0.3) dB and the measured (simulated) CM IL is greater than 20.3 (20.1) dB in 1–10 GHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2629–2633, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27110
Reduced‐cost design optimization of antenna structures using adjoint sensitivity
Authors: Koziel Slawomir , Ogurtsov Stanislav
Published: August 2012

We discuss a simple and yet robust algorithm for electromagnetic (EM) simulation‐driven design optimization of antennas. Our procedure exploits adjoint sensitivities to obtain gradient information without extra EM simulations as well as adaptive algorithm that adjusts the search radius for optimizing the linear model of the antenna. The proposed technique is capable of yielding an optimized antenna design at a much lower computational cost than a benchmark algorithm, Matlab's fminimax, also using adjoint sensitivities. Our approach is demonstrated using two antenna design cases: a planar inverted‐F antenna and a wideband hybrid antenna. The design time savings are between 60 and 75% with respect to the benchmark method. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2594–2597, 2012; this online at wileyonlinelibrary.com. DOI 10.1002/mop.27112
Circularly polarized SIW square ring‐slot antenna for X‐band applications
Authors: Lacik Jaroslav
Published: August 2012

In this letter, a single‐layer circularly polarized substrate integrated waveguide (SIW) square ring‐slot antenna operating in the X‐band is proposed.The circularly polarized wave is generated by a combination of a shortened square ring‐slot etched in the SIW top wall and a shorting via placed between the area bounded by the ring and the SIW bottom wall. Experimental results prove that the antenna with a coax‐to‐SIW transition radiates a right‐hand circularly polarized (RHCP) wave and it achieves the impedance bandwidth of 10.3% for the reflection coefficient less than –10 dB, the axial ratio (AR) bandwidth of 2.6% for AR less than 3 dB, and the RHCP gain 8.0 dBi. The proposed antenna has the advantage of conventional planar structures including low profile, light weight, and easy low cost fabrication. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2590–2594, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27113
A multistandard dual‐mode fully‐integrated miniature, low‐power‐consumption 860–960 MHz CMOS RFID reader for mobile communications, sensing, and networking
Authors: Lee Sanghun , Kwon Hyukje , Ryu Changho , Kim Sungwan , Kang Kyoungyong , Chun Seonghun , Lee Pyunghan , Nguyen Cam
Published: August 2012

A fully‐integrated single‐chip radio frequency identification (RFID) reader consisting of zero‐IF receiver, direct up‐conversion transmitter, sigma‐delta phase‐locked loop synthesizer, and modulation/demodulation (MODEM) module has been developed using 0.18 μm CMOS process.The RFID reader operates from 860–960 MHz in steps of 100/200 kHz, supporting a multiband global standard suitable for USA, Europe, and Korea for both passive and active communication. It is specifically designed to achieve small size, low spur levels, low power consumption, and complete integration while meeting requirements for short‐range applications. The developed reader exhibits transmitting output power of −7.4 dBm controllable over 15 dB range, receiver's P1dB of −7 dBm, sensitivity of −70 dBm, and IF spectral purity of more than 46.4 dBc at frequencies greater than 140.625 Hz away. The complete RFID reader including transmitter, receiver, synthesizer, ADC, DAC, and MODEM occupies 10.9 mm2 and consumes 116.18 mW. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2487–2491, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27117
A three‐frequency feed for millimeter wave radiometry
Authors: Hoppe D. J. , Khayatian B. , Sosnowski J. B. , Bruneau P. , Johnson A. , Reising S. C. , Brown S. T.
Published: August 2012

A high‐performance millimeter‐wave feed, designed for a broad‐band radiometry application is presented. The feed provides three separate output ports in the 87–97 GHz, 125–135 GHz, and 161–183 GHz bands. Measured return loss is better than 20 dB in the upper two bands and 15 dB in the lowest band, and good pattern symmetry is obtained throughout all three frequency bands. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2483–2487, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27118
Numerical and experimental demonstration of a coordinate transformation‐based azimuthal directive emission
Authors: Wu Xinying , Tichit Paul‐Henri , Burokur Shah Nawaz , Kirouane Souad , Sellier Alexandre , de Lustrac André
Published: August 2012

This article deals with the modeling, practical implementation, and characterization of an azimuthal directive antenna around 10 GHz. The design of the antenna is based on transformation optics concept by transforming the radiation of a plane source into an azimuthal radiation. This coordinate transformation procedure is achieved by modifying the electromagnetic properties of the space around the plane source. Metamaterials presenting electric and magnetic resonances are used to produce the effective material parameters necessary for the transformation. S11 parameter and direct far‐field measurements are performed on a fabricated prototype to experimentally demonstrate the narrow beam profile and the beam deflection. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2536–2540, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27122
On the bending effects on artificial magnetic conductors
Authors: Khaleel Haider R. , Al‐Rizzo Hussain M. , Rucker Daniel G.
Published: August 2012

In this letter, we present the performance of a typical artificial magnetic conductor (AMC) under different bending extents. Square patch array‐based AMC is employed as a benchmark to demonstrate the dependence of AMC characteristics on the degree of curvature. We show that increasing the extent of bending leads to a shift to a higher resonance frequency and bandwidth degradation which suggests the importance of such analysis when designing AMC structures for conformal applications. Finite element method full wave electromagnetic solver has been employed to extract the reflection phase profile of the structure under study. To the best of the authors' knowledge, this kind of study is being reported for the first time. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2503–2505, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27124
Small‐size WWAN handset antenna disposed at a small notch in the system ground plane
Authors: Wong Kin‐Lu , Kao Yeh‐Chun , Chu Fang‐Hsien
Published: August 2012

An internal WWAN (824–960/1710–2170 MHz) handset antenna suitable to be disposed at a small notch of 35 × 6 mm2 in the system ground plane of the handset is presented.Also, the antenna has a low profile of 3 mm above the main circuit board on which the system ground plane is printed. That is, the antenna occupies a small volume of 35 × 6 × 3 mm3 or 0.63 cm3 only (much less than 1 cm3). To fit in the small notch, a quarter‐wavelength gap‐coupled loop antenna is applied, which not only can be configured into a compact configuration but also can be in proximity to the surrounding ground plane. With the aid of a matching network, which is comprised of a series chip inductor and a band‐stop matching circuit, two wide operating bands to, respectively, cover the GSM850/900 and GSM1800/1900/UMTS operation are obtained. Details of the proposed antenna are described. The applied techniques in achieving wideband operation with a small antenna size are discussed. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2498–2503, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27125
A novel microstrip lowpass filter using compact microstrip resonant cells and uniquely shaped defected ground structures
Authors: Yang Yang , Zhu Xi , Karmakar Nemai C.
Published: August 2012

A novel microstrip lowpass filter (LPF) with high selectivity and wide stopband is proposed in this letter.The proposed LPF consists of three compact microstrip resonant cells, two E‐shaped feed‐lines on the top layer and four defected ground structure (DGS) slots on the ground plane. The top layer LPF is designed to have a sharp roll‐off characteristic, whereas the engineered DGS slots on the ground plane are used to reduce the passband ripples and extend the stopband bandwidth of the proposed LPF. A selectivity of 53.4 dB/GHz is achieved. The stopband with an attenuation level of 20 dB is obtained from 2.96 to 13.2 GHz. The filter is optimally designed, fabricated, and measured. Both simulated and measured results are presented, which show a good agreement between simulation and measurement. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2462–2464, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27126
A tunable planar inverted‐f antenna for digital video broadcast‐handheld applications
Authors: Manteghi Majid
Published: August 2012

A compact varactor‐tuned planar inverted‐F antenna is introduced for digital video broadcast‐handheld (DVB‐H) applications. The antenna size is 20 × 40 × 5 mm3, making it particularly suitable as an internal antenna. A full‐wave simulator is used to calculate the scattering matrix of the antenna as a two port network. A circuit model including the two‐port antenna and its tuning circuitry is simulated using a circuit simulator. The simulation results show that the antenna is continuously tunable within the entire frequency range of the DVB‐H standard, 470–702 MHz. The antenna is prototyped and tested. The measured results are in agreement with the simulation data. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2635–2638, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.21728
3.5 GHz WiMAX GaN doherty power amplifier with second harmonic tuning
Authors: Fang Jie , Moreno Jorge , Quaglia Roberto , Camarchia Vittorio , Pirola Marco , Guerrieri Simona Donati , Ramella Chiara , Ghione Giovanni
Published: August 2012

The article presents the design, realization, and experimental validation of a GaN‐based hybrid Doherty power amplifier for WiMAX base‐stations at 3.5 GHz. The amplifier exploits, for the first time as far as authors' knowledge goes, a second harmonic tuning scheme designed to further improve the efficiency in the Doherty region. The amplifier is based on a packaged GaN HEMT from Cree, and shows a saturated output power exceeding 43.2 dBm (21.5 W), a Doherty high‐efficiency region in excess of 6 dB output back‐off, with a first peak and maximum drain efficiency at saturation of 55 and 61%, respectively. The amplifier, with baseband digital predistortion, is compliant with the standard emission mask in the presence of a 9 dB peak to average power ratio WiMAX input and exhibits a weighted efficiency as high as 40%. The performances of the designed amplifier favorably compare with the state of the art for the same application. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2601–2605, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27132
Fabrication of diamond‐structured multiceramic coupling photonic crystal and its ultra‐wide bandgap properties
Authors: Liang Qingxuan , Li Dichen , Yang Gai
Published: August 2012

The diamond‐structured multiceramic coupling photonic crystal (PC) containing alumina and yttira simultaneously was successfully fabricated by stereolithography and multistep gel‐casting process. Compared with the bandgap width of the alumina PC or the yttira PC separately, the bandgap width of the multiceramic coupling PC is 8.5 GHz that became 134.9% of the alumina PC's bandgap width and 146.6% of the yttira PC's bandgap width along the direction Γ‐X<100>, and the resulting gap‐midgap ratio significantly increased too. These results agreed well with the simulation results by finite integration technique. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2569–2572, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27134
A compact hairpin bandpass filter using multilayer stripline folded quarter‐wavelength resonators
Authors: Gu Xiaowei , Yang Lingyun , Bao Xiaoan , Yu Chenghai , Shi Qingjiang
Published: August 2012

This article presents a compact hairpin bandpass filter using multilayer stripline folded quarter‐wavelength resonators in a low‐temperature cofired ceramic substrate.Using the new structure designs accomplish the vertical coupling in multilayer system, the size of the proposed filter can be reduced about 50% compared to an equivalent single‐layer hairpin resonator filter. As an example, an L‐band filter centered at 1.10 GHz with a fractional bandwith of 13.5% is designed, fabricated, and measured. The measured results of the fabricated filter agree very well with the electromagnetic simulations. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2627–2629, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27139
Design of a patch antenna with dual‐band radar cross‐section reduction
Authors: Miao Zhilong , Huang Cheng , Ma Xin , Pu Mingbo , Ma Xiaoliang , Zhao Qin , Luo Xiangang
Published: August 2012

In this article, we present a method for reducing radar cross‐section (RCS) of a patch antenna in two frequency bands. This method is based on the absorbing metamaterial loaded around the patch exciting source. The metamaterial is composed of double‐square‐loop structure inserted with resistors, which can absorb incident wave at two frequency bands. The RCS characteristic of the proposed antenna is investigated by numerical simulation and measurement. Simulated result shows that RCS is obviously reduced by about 8 dBsm at 5.8 GHz within the operating frequency of the antenna and 9 GHz out of working band, compared with the conventional patch antenna. In addition, it is found that the loaded metamaterial almost have no negative influences on the antenna performance, and the gain of the antenna is improved by 0.6 dB. There is a good agreement between measured and simulated results. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2516–2520, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27144
Modeling of electronic transport in metallic carbon nanotube interconnects in the presence of electron‐phonon interactions
Authors: Parkash V. , Goel A. K.
Published: August 2012

Metallic carbon nanotubes are being considered as a candidate to potentially replace copper as an interconnect material in next generation nanotechnology integrated circuits.In this article, we have examined the electronic transport behavior in metallic carbon nanotubes using a self consistent nonequilibrium Green's function method. We have included the effects of electron‐phonon interactions in our model. Results show that conductivity decreases in the ballistic limit due to localized disorder effects even with a weak disorder potential. We are also able to show that optical phonons (both LO and TO modes) are the dominant mechanisms that govern the mean free path of conduction in the nanotube. Our calculations show an excellent agreement with experimental results available in the literature. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2477–2483, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27145
A novel microstrip parallel‐coupled line structure for ultrawideband microwave filters
Authors: Shaman Hussein , Hong Jia‐Sheng
Published: August 2012

A novel configuration of microstrip three parallel‐coupled line structure is proposed in this letter. This new structure consists of only one section of three parallel‐coupled lines to design a compact ultrawideband (UWB) bandpass filter to obtain the Federal Communications Commission's spectrum mask. To create transmission zeros around the desired UWB passband, the middle line of the three coupled lines is extended and shortened to ground at one end. As a result, this filter significantly improves the selectivity of both edges of the UWB passband and the out‐of‐band characteristics. For verification, the proposed filter is designed, simulated, and fabricated where excellent agreement is obtained. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2510–2513, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27146
Miniaturized planar ultra‐wideband antenna on a trapezoidal ground fed with a tapered microstrip line
Authors: Zhang Yangjun , Hara Masayuki
Published: August 2012

A miniaturized planar ultra‐wideband (UWB) antenna is proposed.The antenna is fed with a tapered microstrip line. A trapezoidal ground pattern is studied to improve impedance matching over the UWB frequency range. The total size of proposed antenna is 22 × 25 mm2, which is much smaller than the antenna with a conventional square ground. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2468–2472, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27148
Pin diode‐based variable directional coupler
Authors: Bulja Senad , Grebennikov Andrei
Published: August 2012

Analysis and design of a novel variable directional coupler based on a parallel line directional coupler using the even‐odd mode technique are proposed. In this coupler, the variation of coupling is achieved using a PIN diode, connected to the nominally coupled port of a parallel line directional coupler, while the output is derived from the normally isolated port. To verify the theory, a parallel microstrip line coupler is fabricated on a substrate with εr = 3.66, h = 762 μm, and tanδ = 0.006 and measured. The measured results show a variation in the transmission coefficient of nearly 20 dB, while at the same time, the change in the direct arm insertion loss is lower than 0.2 dB. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2643–2646, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27151
Microwave doppler radar for heartbeat detection vs electrocardiogram
Authors: Obeid Dany , Zaharia Gheorghe , Sadek Sawsan , El Zein Ghaïs
Published: August 2012

This article presents a contact‐less system to detect the heartbeat activity from a distance of 1 m. The proposed system is based on using a vector network analyzer. Measurements are performed at 16 GHz for different power levels between 0 and −25 dBm. Results for two S‐parameters are obtained and compared to an electrocardiogram simultaneous signal in terms of heartbeat rate and heart rate variability. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2610–2617, 2012; this online at wileyonlinelibrary.com. DOI 10.1002/mop.27152
Pad‐to‐pad isolation of vertical interconnects using magnetically aligned anisotropic conductive adhesive
Authors: Moon Sungwook
Published: August 2012

Self‐alignment of vertical interconnects using a magnetically aligned anisotropic conductive adhesive (MA‐ACA) is a unique method, which is useful in high‐density electronic applications.This material is created by magnetic interaction between loading conductive particles in an epoxy medium. To analyze electromagnetic interference between adjacent I/O pads, a lumped component model was suggested, consisting of shunt capacitance, parallel capacitance, series resistance, series inductance, and coupling capacitance. The equivalent circuit model was validated through the measurement of test samples with MA‐ACA interconnects. Also, the pad‐to‐pad isolation of the MA‐ACA was compared to that of lead/tin solder connections. As a result, at high frequencies the pad‐to‐pad isolation of the MA‐ACA interconnects was observed to be mainly degraded by a larger coupling capacitance due to the presence of metallic interconnects at a transition region. Therefore, a packaging approach using the characterized RF performance of the MA‐ACA interconnects is expected to be designed for high‐density electronic circuitry. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2606–2610, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27153