bluuebunny/crossref_metadata_2025 huggingface dataset:
Wide‐dynamic‐range neurons are heterogeneous in windup responsiveness to changes in stimulus intensity and isoflurane anesthesia level in mice
Authors: Guan Yun , Raja Srinivasa N.
Published: March 2010

The windup phenomenon in wide‐dynamic‐range (WDR) neurons represents a short‐term neuronal sensitization to repetitive noxious inputs that may share similar mechanisms with those that trigger the development of persistent pain and hyperalgesia. Some WDR cells are readily sensitized and express prominent windup (windup+), whereas others do not (windup−). We recorded extracellular single‐unit activity of deep laminae WDR neurons (350–700 μm) in C57BL/6 mice to determine how changes in stimulus intensity (1× and >2× C‐component threshold, n = 53) and concentrations of isoflurane anesthesia (2.0% and 1.0%, n = 30) might differently modulate windup responsiveness in windup+ and windup− cells. Two principally different analysis methods [absolute windup (the number of action potentials) and relative windup (the percentage of action potentials evoked by the first stimulus of the train)] were used to interpret windup data. We observed that increasing the stimulus intensity and decreasing the isoflurane concentration: 1) facilitated windup generation at 0.2‐Hz stimulation and significantly enhanced absolute windup at both 0.2‐Hz and 0.5‐Hz stimulation predominantly in windup+ cells but did not confer windup capability on windup− cells and 2) significantly increased relative windup at 0.2‐Hz, but not 0.5‐Hz, stimulation in windup+ cells. Our findings advance our understanding of the neurobiology of deep WDR neurons in mice and demonstrate that two populations of cells differ in their windup responsiveness to changes in experimental conditions. We also elucidate the usefulness and potential limitations of two widely used methods for calculating and presenting windup data. © 2010 Wiley‐Liss, Inc.
Brain‐derived neurotrophic factor inhibits cell cycle reentry but not endoplasmic reticulum stress in cultured neurons following oxidative or excitotoxic stress
Authors: Boutahar Nadia , Reynaud Evelyne , Lassabliere François , Borg Jacques
Published: March 2010

Neurotrophins protect neurons against glutamate and oxidative stress, but the underlying mechanism remains unclear. We investigated the neuroprotective role of the neurotrophin brain‐derived neurotrophic factor (BDNF) in neuronal cultures subjected to NMDA or H2O2 toxicity and analyzed the molecular mechanisms involved, particularly those related to regulation of cell cycle or endoplasmic reticulum (ER) stress. Preincubation with BDNF of cortical neuron cultures prevented NMDA‐ or H2O2‐induced neuronal death as well as MAPK‐ERK1/2 activation. Inhibition of phosphatidylinositol 3‐kinase (PI3‐K) abolished the protective effect of BDNF. NMDA and H2O2 induced activation of cell cycle reentry regulators such as retinoblastoma (Rb) protein and E2F1 transcription factor. However, BDNF abolished the activation of both factors. NMDA‐induced expression of chaperone encoding gene BIP was slightly inhibited by BDNF, but it did not affect expression of ER stress protein CHOP. Our results suggest that BDNF neuroprotection may be mediated through inhibition of Ras‐MAPK pathway and cell cycle reentry during oxidative or excitotoxic stress responses. However, BDNF did not modify expression of ER stress signal induced by NMDA. © 2010 Wiley‐Liss, Inc.
Rostral brain axonal injury in congenital central hypoventilation syndrome
Authors: Kumar Rajesh , Macey Paul M. , Woo Mary A. , Harper Ronald M.
Published: March 2010

Brain injury underlying the state‐related loss of ventilatory drive, autonomic, cognitive, and affective deficits in congenital central hypoventilation syndrome (CCHS) patients appears throughout the brain, as demonstrated by magnetic resonance (MR) T2 relaxometry and mean diffusivity studies. However, neither MR measure is optimal to describe types of axonal injury essential for assessing neural interactions responsible for CCHS characteristics. To evaluate axonal integrity and partition the nature of tissue damage (axonal vs. myelin injury) in CCHS, we measured water diffusion parallel (axial diffusivity) and perpendicular (radial diffusivity) to rostral brain fibers, indicative of axonal and myelin changes, respectively, with diffusion tensor imaging (DTI). We performed DTI in 12 CCHS (age 18.5 ± 4.9 years, 7 male) and 30 control (17.7 ± 4.6 years, 18 male) subjects, using a 3.0‐Tesla MR imaging scanner. Axial and radial diffusivity maps were calculated, spatially normalized, smoothed, and compared between groups (analysis of covariance; covariates, age and gender). Significantly increased radial diffusivity, primarily indicative of myelin injury, emerged in fibers of the corona radiata, internal capsule, corpus callosum, hippocampus through the fornix, cingulum bundle, and temporal and parietal lobes. Increased axial diffusivity, suggestive of axonal injury, appeared in fibers of the internal capsule, thalamus, corona radiata, and occipital and temporal lobes. Multiple brain regions showed both higher axial and radial diffusivity, indicative of loss of tissue integrity with a combination of myelin and axonal injury, including basal ganglia, bed nucleus, and limbic, occipital, and temporal areas. The processes underlying injury are unclear, but likely stem from both hypoxic and developmental processes. © 2010 Wiley‐Liss, Inc.
μ‐Opioid receptor knockout mice are insensitive to methamphetamine‐induced behavioral sensitization
Authors: Shen Xine , Purser Chris , Tien Lu‐Tai , Chiu Chi‐Tso , Paul Ian A. , Baker Rodney , Loh Horace H. , Ho Ing K. , Ma Tangeng
Published: March 2010

Repeated administration of psychostimulants to rodents can lead to behavioral sensitization. Previous studies, using nonspecific opioid receptor (OR) antagonists, revealed that ORs were involved in modulation of behavioral sensitization to methamphetamine (METH). However, the contribution of OR subtypes remains unclear. In the present study, using μ‐OR knockout mice, we examined the role of μ‐OR in the development of METH sensitization. Mice received daily intraperitoneal injection of drug or saline for 7 consecutive days to initiate sensitization. To express sensitization, animals received one injection of drug (the same as for initiation) or saline on day 11. Animal locomotor activity and stereotypy were monitored during the periods of initiation and expression of sensitization. Also, the concentrations of METH and its active metabolite amphetamine in the blood were measured after single and repeated administrations of METH. METH promoted significant locomotor hyperactivity at low doses and stereotyped behaviors at relative high doses (2.5 mg/kg and above). Repeated administration of METH led to the initiation and expression of behavioral sensitization in wild‐type mice. METH‐induced behavioral responses were attenuated in the μ‐OR knockout mice. Haloperidol (a dopamine receptor antagonist) showed a more potent effect in counteracting METH‐induced stereotypy in the μ‐OR knockout mice. Saline did not induce behavioral sensitization in either genotype. No significant difference was observed in disposition of METH and amphetamine between the two genotypes. Our study indicated that the μ‐opioid system is involved in modulating the development of behavioral sensitization to METH. © 2010 Wiley‐Liss, Inc.
Impaired neurogenesis is an early event in the etiology of familial Alzheimer's disease in transgenic mice
Authors: Demars Michael , Hu Yuan‐Shih , Gadadhar Archana , Lazarov Orly
Published: March 2010

Formation of new neurons in the adult brain takes place in the subventricular zone and in the subgranule layer of the dentate gyrus throughout life. Neurogenesis is thought to play a role in hippocampus‐ and olfaction‐dependent learning and memory. However, whether impairments in neurogenesis take place in learning and memory disorders, such as Alzheimer's disease, is yet to be established. Importantly, it remains to be elucidated whether neurogenic impairments play a role in the course of the disease or are the result of extensive neuropathology. We now report that transgenic mice harboring familial Alzheimer's disease‐linked mutant APPswe/PS1ΔE9 exhibit severe impairments in neurogenesis that are evident as early as 2 months of age. These mice exhibit a significant reduction in the proliferation of neural progenitor cells and their neuronal differentiation. Interestingly, levels of hyperphosphorylated tau, the cytotoxic precursor of the Alzheimer's disease hallmark neurofibrillary tangles, are particularly high in the neurogenic niches. Isolation of neural progenitor cells in culture reveals that APPswe/PS1ΔE9‐expressing neurospheres exhibit impaired proliferation and tau hyperphosphorylation compared with wildtype neurospheres isolated from nontransgenic littermates. This study suggests that impaired neurogenesis is an early critical event in the course of Alzheimer's disease that may underlie memory impairments, at least in part, and exacerbate neuronal vulnerability in the hippocampal formation and olfaction circuits. Furthermore, impaired neurogenesis is the result of both intrinsic pathology in neural progenitor cells and extrinsic neuropathology in the neurogenic niches. Finally, hyperphosphorylation of the microtubule‐associated protein tau, a critical player in cell proliferation, neuronal maturation, and axonal transport, is a major contributor to impaired neurogenesis in Alzheimer's disease. © 2010 Wiley‐Liss, Inc.
Characterization of sialylated and fucosylated glycopeptides of β2‐glycoprotein I by a combination of HILIC LC and MALDI MS/MS
Authors: Kondo Akira , Thaysen‐Andersen Morten , Hjernø Karin , Jensen Ole N.
Published: March 2010

Characterization of low microgram levels of glycoprotein remains a challenge due to extensive heterogeneity of the conjugated N‐glycans at each individual glycosylation site. We present an optimized, sensitive workflow for glycopeptide isolation and characterization that exploits the complementary features of RP (Poros R2) and hydrophilic (zwitter‐ionic hydrophilic interaction chromatography) chromatographic resins. The glycopeptide analysis workflow was applied to human β2‐glycoprotein I (β2‐GPI, apolipoprotein H), which contains multiple N‐glycosylation sites. Conditions for rapid proteolytic digestion of β2‐GPI using low‐specificity proteases were optimized to detect β2‐GPI glycopeptides by MS. We demonstrate the importance of ensuring sufficient column capacity of both hydrophobic and hydrophilic stationary phases for optimal glycoprofiling by MS. The enriched glycopeptides were characterized using MALDI quadrupole TOF MS/MS. A total of 23 glycan structures, including sialylated bi‐ and tri‐antennary complex type glycans, were characterized at three N‐glycosylation sites, namely Asn‐143, Asn‐174 and Asn‐234, of β2‐GPI. Further exploration of the complementary nature of RP and HILIC stationary phases for glycopeptide isolation prior to MS analysis may eventually enable systematic analysis of complex glycoprotein samples in functional proteomic research and advance our understanding of the biological role of protein glycosylation.
Determination of melamine in milk powder using zwitterionic HILIC stationary phase with UV detection
Authors: Nkem Ihunegbo Felicia , Tesfalidet Solomon , Jiang Wen
Published: March 2010

A hydrophilic interaction liquid chromatography‐UV method was developed for the determination of melamine in milk powder. Sulfobetaine type zwitterionic hydrophilic interaction liquid chromatography stationary phase was used to achieve straightforward separation of melamine in milk powder without any sample derivatization or addition of ion‐pair reagent. The sample preparation was simple and fast with the steps of acetonitrile/perchloric acid extraction‐centrifugation‐filtration. No SPE or other pre‐concentration procedure was required. By using large volume sample injection and choosing low UV wavelength (210 nm), the LOD and LOQ were 0.005 and 0.015 μg/mL for melamine standards, and 0.02 and 0.06 μg/mL for the spiked milk extracts. The LOD and LOQ of the latter correspond to 0.95 and 2.2 μg/g melamine in the milk powder. The correlation coefficients for melamine standard, pre‐spiked milk extracts and post‐spiked milk extracts in the range of 0–0.5 μg/mL were 0.9978, 0.9976 and 0.9995, respectively. This newly developed method is sensitive and cost effective, therefore, suitable for screening of melamine in tainted milk products.
Hyposmia in progressive supranuclear palsy
Authors: Silveira‐Moriyama Laura , Hughes Graham , Church Alistair , Ayling Hilary , Williams David R. , Petrie Aviva , Holton Janice , Revesz Tamas , Kingsbury Ann , Morris Huw R. , Burn David J. , Lees Andrew J.
Published: March 2010

Previous studies suggested that olfaction is normal in progressive supranuclear palsy (PSP). We applied the University of Pennsylvania Smell Identification Test (UPSIT) to 36 patients with PSP who scored more than 18 on the Mini Mental State Examination (MMSE), 140 patients with nondemented Parkinson's disease (PD) and 126 controls. Mean UPSIT scores in PSP were lower than in controls (P < 0.001) but higher than in PD (P < 0.001) after adjusting for age, gender, and smoking history. For patients with PSP, UPSIT scores correlated with MMSE (r = 0.44, P = 0.006) but not disease duration (P = 0.6), motor subscale of the Unified Parkinson's Disease Rating Scale (P = 0.2), or Frontal Assessment Battery (P = 0.5). The brains of six of the patients with PSP were examined postmortem and all revealed neurofibrillary tangles and tau accumulation in the rhinencephalon, although only three had hyposmia. Further prospective studies including patients with early PSP and PSP‐P with postmortem confirmation might help clarify if smell tests could be useful when the differential diagnosis lies between PD and PSP. © 2010 Movement Disorder Society
Design, Synthesis, and Evaluation of Antineoplastic Activity of Novel Carbocyclic Nucleosides
Authors: Helguera Aliuska M. , Rodríguez‐Borges J. E. , Caamaño Olga , García‐Mera Xerardo , González Maykel Pérez , Cordeiro M. Natália D. S.
Published: March 2010

Cancer is the leading cause of death among men and women under age 85. Every year, millions of individuals are diagnosed with cancer. But finding new drugs is a complex, expensive, and very time‐consuming task. Over the past decade, the cancer research community has begun to address the in silico modeling approaches, such as Quantitative Structure‐Activity Relationships (QSAR), as an important alternative tool for targeting potential anticancer drugs. With the compilation of a large dataset of nucleosides synthesized in our laboratories, or elsewhere, and tested in a single cytotoxic assay under the same experimental conditions, we recognized a unique opportunity to attempt to build predictive QSAR models. Early efforts with 2D classification models built from part of this dataset were very encouraging. Here we report a further detailed evaluation of classification models to flag potential anticancer activities derived from a variety of 3D molecular representations. A quantitative 3D‐model model that discriminates anticancer compounds from the inactive ones was attained, which allowed the correct classification of 82 % of compounds in such a large and diverse dataset, with only 5 % of false inactives and 11 % of false actives. The model developed here was then used to select and design a new series of nucleosides, by classifying beforehand them as active/inactive anticancer compounds. From the compounds so designed, 22 were synthesized and evaluated for their inhibitory effects on the proliferation of murine leukemia cells (L1210/0), of which 86 % were well‐classified as active or inactive, and only two were false actives, corroborating the good predictive ability of the present discriminant model. The results of this study thus provide a valuable tool for the design of novel potent anticancer nucleoside analogues.
Structure‐Activity Relationship Studies of a Number of α1‐Adrenoceptor Antagonists and Antiarrhythmic Agents
Authors: Nowaczyk Alicja , Przybylski Rafał , Kulig Katarzyna , Malawska Barbara
Published: March 2010

Arylpiperazines represent one of the most studied classes of α1‐adrenoceptor (α1‐AR) antagonists. Currently, α1‐AR antagonists are useful in the treatment of benign prostatic hyperplasia, lower urinary tract symptoms or cardiac arrhythmia. The activity of various derivatives of 1‐[3‐(4‐arylpiperazin‐1‐yl)propyl]pyrrolidin‐2‐one as α1‐adrenergic receptor antagonists and antiarrhythmic (AA) agents was described using the qualitative inverse Structure Activity Relationship (SAR) model. The three‐dimensional structures of the pyrrolidin‐2‐one derivatives in the basic form were obtained using AM1 semi‐empirical quantum chemical calculations. All the molecules were geometry‐optimized until the root‐mean‐square (RMS) gradient value was smaller than 10−6a.u. Single‐point energy (SPE) calculations were performed at the DFT/B3LYP level of theory using the 6‐31G** basis set. The main focus of this inverse SAR study is to find which features cause enhancing of antiarrhythmic properties between subtly different types of activity (α1‐adrenoreceptor antagonists and antiarrhythmic activities). Our SAR study involves the charge distribution in the plane of the pharmacophore model for α1‐AR. Suitable maps of the electrostatic potential were plotted based on the electronic and nuclear charge distribution obtained from the energy calculations. The results of this modelling study indicate that if the terminal arylpiperazine moiety is surrounded by regions of negative electrostatic potential, then the antiarrhythmic activity is blocked.
Equivalence of space‐fed microstrip antenna array with horn antenna
Authors: Bhide Rahul , Kumar Girish
Published: March 2010

Equivalence between space‐fed microstrip antenna arrays and horn antenna is established. A method is proposed to determine the array height from the fed microstrip antenna and correction of phase error across the array aperture. A 25‐element array with elements arranged in a 5 × 5 rectangular grid is designed. Simulated and measured results are presented. Space‐fed arrays are easy to fabricate, have less weight, high gain, and low side lobe levels. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1180–1183, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25092
A new time domain solution for the multiple diffraction of spherical waves by an array of nonperfectly conducting wedges for UWB signals
Authors: Liu Peng , Long Yunliang
Published: March 2010

A time domain (TD) solution for the analysis of multiple diffraction of spherical waves after an array of nonperfectly conducting wedges with different interior angles is presented.The proposed TD solution is based on the representation of the inverse Laplace transform of the corresponding frequency domain solution in closed form, as it is given by a hybrid of the uniform theory of diffraction (UTD)‐physic optics (PO) solution. The new formulation, validated with the results from technical literature, does not need to incorporate the TD version of the higher‐order diffraction coefficients and allows for the calculation of large number of wedges. It has the major advantage in terms of the mathematical complexity and computation efficiency when compared with other TD solutions. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1006–1008, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25094
Circular‐slotted microstrip antenna for GPS
Authors: Sun Xu‐Bao
Published: March 2010

To meet the required precision and reliability for global positioning systems, a probe‐feed dual‐band circularly polarized (CP) microstrip antenna is proposed.This new microstrip antenna design uses a circular patch that is printed on a two‐layer substrate consisting of an FR4 dielectric layer and a foam layer, and cutting a crossed‐slot and an open ring‐slot in the circular patch. When compared with the conventional dual‐band CP antenna with two patches among substrate materials, not only is the performance of the antenna improved but also its fabrication becomes easier. The simulated and measured results indicate the validity of the design. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 999–1000, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25095
Printed wide‐slot antenna with high polarization purity for wideband applications
Authors: Naser‐Moghadasi Mohammad , Bayderkhani Reza , Dadashzadeh Gholamreza , Virdee Bal S.
Published: March 2010

This article describes a novel compact wideband slot antenna comprising of an E‐shaped patch that is excited with a trident‐shaped microstrip feed‐line structure. The antenna design exhibits a very wide operating bandwidth of over 163% with S11 < −10 dB in the frequency range 2–19.95 GHz. The antenna's radiation characteristics are stable across the 2–12 GHz band. The proposed antenna exhibits high polarization purity with cross‐polarization level that is well below −50 dB. A comprehensive parametric study was performed on the antenna to fully understand the effects of various antenna parameters that enable optimization of the antenna's performance. This antenna easily fulfills the requirements for ultra‐wideband wireless communication systems as specified by federal communication commission over the designated band 3.1–10.6 GHz. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1001–1006, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25096
An efficient time‐domain method analysis of quasiperiodic structures by a finite‐element tearing and interconnecting algorithm
Authors: Du L. , Chen R. S. , Ye Z.B. , Yang Y.
Published: March 2010

Based on the finite‐element approximation and nonoverlapping domain decomposition, an efficient tearing and interconnecting algorithm of the finite‐element time‐domain method is presented. Using edge‐based finite element, the method divides the computation domain into several nonoverlapping subdomains and computes electric fields in each subdomain by solving the vector curl–curl wave equation. Adjacent subdomains are related to each other by Dirichlet and Neumann boundary condition. By use of the repetition of the quasiperiod structures, the method further reduces the memory requirement and CPU time. The time‐dependent formulation employs an unconditional stable time‐integration method based on the Newmark‐beta method. An anisotropic perfectly matched layers absorbing material terminated by the first‐order boundary condition is applied for the truncation of lattices. Numerical results demonstrate that our proposed method is extremely efficient for the time‐domain analysis of the quasiperiodic structures, such as electromagnetic band gap structures.© 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1072–1078, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.25100
Wireless network based on radio‐over‐fiber with optical carrier reuse by fiber grating
Authors: Yiying Gu , Shanfeng Li , Xin Luo , Xiuyou Han , Mingshan Zhao
Published: March 2010

This article presents a vector signal transmission architecture for wireless network based on radio‐over‐fiber system. Partly double sideband carrier suppressed modulation scheme was used to generate optical frequency doubled microwave while the same optical carrier was reused via a fiber grating for up‐link transmission in base station (BS). The 5 GHz microwave carrying 1 Mbps 8PSK‐vector signal was up‐converted to 10 GHz in BS with the vector signal conversion from 8PSK to QPSK. Also, a 50 GHz millimeter‐wave was generated that can be seen from the optical spectra. Such a system shows simple configuration and is cost‐efficient. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1145–1148, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25103
KTN ferroelectrics‐based microwave tunable phase shifter
Authors: Zhang Ling Yan , Laur Vincent , Pothier Arnaud , Simon Quentin , Laurent Paul , Martin Noham , Guilloux‐Viry Maryline , Tanné Gérard
Published: March 2010

This letter presents the design, fabrication, and measurement of a KTa1‐xNbxO3‐ (KTN‐) based phase shifter. This loaded‐line phase shifter has insertion losses of about 7.36 dB at zero bias and 10 GHz, a return loss greater than 12 dB over the frequency range 1–16 GHz and a relatively high differential phase shift of about 88° for a 120 V DC bias at 10 GHz. The enhancement of performances observed by comparison with those presented by the KTN‐based phase shifters positions KTN materials as a serious alternative to Ba1‐xSrxTiO3 ones for microwave agility applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1148–1150, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25104
Efficient DRW antenna for quasi‐optics feed in W‐band imaging radiometer system
Authors: Kim Won‐Gyum , Thakur Jay Prakash , Kim Yong‐Hoon
Published: March 2010

Modification in tapered dielectric rod waveguide antenna is achieved by the implementation of step change in width in metallic waveguide transition. The proposed antenna has circular symmetric radiation pattern and gain about 15.3 dB with improved return loss and side lobes level at W‐band. It has 10 dB beamwidth 53.2° and 48.6° in the E‐ and H‐plane. Proposed antenna can be used for a millimeter wave quasi‐optics feed array design in W‐band imaging radiometer design. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1221–1223, 2010; Published online in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/mop.25107
An incomplete factorization preconditioner based on shifted Laplace operators for FEM analysis of microwave structures
Authors: Zhu J. , Ping X. W. , Chen R. S. , Fan Z.H. , Ding D. Z.
Published: March 2010

In this article, the tangential vector finite element method combined with the high‐order basis functions is applied for the analysis of electromagnetic problems based on Helmholtz equations. Different from conventional preconditioners, the preconditioner presented in this article is derived based on the shifted Laplace operator, and the diagonally perturbed incomplete factorization is used to approximate the inverse of this operator. Numerical experiments demonstrate that the proposed preconditioner can significantly speed up the iterative convergence of conjugate gradient method for several electromagnetic structures. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1036–1042, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25111
Ultra‐wideband GCPW‐MS‐GCPW driven electrode for low‐cost and wide range application electro‐optic modulators
Authors: El‐Gibari Mohammed , Averty Dominique , Lupi Cyril , Li Hongwu , Toutain Serge
Published: March 2010

Electro‐optic modulators are key components in high bit‐rate optical transmissions. Decreasing the manufacturing cost without damage on performances is one of the most challenging issues for such components. We demonstrate that the electro‐optic modulators based on polymer are compatible with high bandwidth requirements. Indeed, according to the results obtained by numerical simulation and partly validated by experiments, with the via‐free GCPW‐MS‐GCPW electrodes proposed and analyzed in this article, the (400 MHz–67 GHz) bandwidth is achievable with electro‐optic modulators based on suitable polymers. These encouraging results are very useful for low‐cost mass production of polymer‐based electro‐optic modulators for a wide range of applications: digital and analogue high bit‐rate transmissions.© 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1078–1082, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25112
UHF RFID near field reader antenna for item level applications
Authors: Kim Jeong‐Seok , Choi Won‐Kyu , Choi Gil‐Young
Published: March 2010

A UHF band near‐field antenna using microstrip lines and stubs for tagging stacked tags in a smart table is presented. It is shown that a suitable near‐field reader antenna can be designed from signal lines, ground lines, and several stubs to generate coupled electric and magnetic fields. The proposed near‐field reader antenna satisfactorily operates in a UHF radio frequency identification (RFID) smart table, and the measurements show that the antenna is capable of detecting 200 stacked tags in a reading area of 200 mm × 190 mm and achieves a detection rate of 97% when the tags are stacked in a smart table. The proposed UHF RFID smart table is successfully implemented for casino chip management. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1116–1119, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25115
Robust full‐duplex ROF system
Authors: Thomas D. H. , Vilela de Faria G. , von der Weid J. P.
Published: March 2010

We present a simple and robust full‐duplex radio‐over‐fiber (ROF) system using two laser sources with efficient laser frequency stability control enlarging the reliability of the whole system with automatic operation. Error‐free operation was obtained at 52 and 155 Mb/s. The system was successfully tested for ASI/SDI‐coded digital TV transmission at 270 Mb/s. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1009–1013, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25120
Design of a planar ultra‐wideband miniature monopole antenna for wireless USB dongle devices
Authors: Chang Yu‐Chia , Chiu Chien‐Ching
Published: March 2010

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
Dual‐band branch line coupler based on composite right‐/left‐handed transmission lines with series capacitors only
Authors: Park Jinsung , Lee Yongshik
Published: March 2010

This article demonstrates, for the first time, a dual‐band branch line coupler based on composite right‐/left‐handed transmission lines with series capacitors only.The complete elimination of shunt inductors provides a potential for the proposed CRLH transmission lines to be applicable to high frequencies, especially without via‐holes in microstrip lines. Experimental results are in excellent agreements with the simulated results. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1046–1048, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25123
Ultra‐wideband coplanar boat microstrip patch with modified ground plane by using electromagnetic band‐gap structure for wireless communication
Authors: Elsheakh Dalia N. , Elsadek Hala A. , Abdallah Esmat A. , Iskander Magdy , Elhenawy Hadia
Published: March 2010

A new antenna structure using triangular patch alongside a small trapezoidal shape ground plane with proximity fed is proposed in this article. The proposed antenna design provides a bandwidth in the range from 2 < 35 GHz with band discontinuities. Improvement is done in antenna performance by using electromagnetic band‐gap (EBG) structure. First, dumb‐bell shapes as 2D‐EBG are etched in the feeding line. Second, embedded spiral artificial magnetic conductor with four arms to introduce sufficient inductive impedance is done. The resultant bandwidth increases to three times than the original bandwidth and reduces the antenna size as well as enhancing the antenna gain. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1159–1164, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.25129
Novel broadband rectenna using printed monopole antenna and harmonic‐suppressed stub filter
Authors: Hong Tae‐Ui , Oh Kyoung‐Min , Lee Hyun‐Wook , Nam Hee , Yun Tae‐Soon , Lee Dae‐Sung , Hwang Hak‐In , Lee Jong‐Chul
Published: March 2010

This article reports a novel broadband rectifying antenna (rectenna) using the printed monopole antenna and the band‐pass stub band‐pass filter, which is designed in the microstrip line structure at 2.45 GHz for the wireless transmission of microwave power.We suggest a novel H‐shape printed monopole antenna with size reduction of the radiator and the ground plane using surface current distribution, and a broadband stub band‐pass filter with suppression of the second harmonic. The rectifying circuit with stub filter doesn't need additional area because it is fabricated on the ground plane, which is widened to acquire broadband characteristic of the monopole antenna. The RF‐to‐DC conversion efficiency of 66% is obtained by using a load resistor of 270 Ω at 2.45 GHz. Also, the conversion efficiency is maintained from 2 GHz to 3 GHz above 50%. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1194–1197, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25130
60 GHz high resistivity silicon on insulator interdigitated dipole antenna
Authors: Barakat M. H. , Delaveaud C. , Ndagijimana F.
Published: March 2010

The performance of a 60 GHz interdigitated dipole antenna integrated on SOI is described. The SOI substrate effect has been compensated by the introduction of an interdigitated structure. Good dipole matching impedance at 60 GHz over a bandwidth of 8% is obtained. Backside substrate metallization has been used to improve the radiation properties. A novel test method is used to measure the gain patterns of the dipole. The resulting measured radiation efficiency is 80% with a gain around 3 dBi at 60 GHz. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1197–1201, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25132
PO‐based characteristic basis finite element method (CBFEM‐PO)—A parallel, iteration‐free domain decomposition algorithm using perfectly matched layers for large‐scale electromagnetic scattering problems
Authors: Ozgun Ozlem , Mittra Raj , Kuzuoglu Mustafa
Published: March 2010

In this article, we introduce a new type of Characteristic Basis Finite Element Method (CBFEM), which is based on the concepts of Physical Optics (PO) and Perfectly Matched Layers (PMLs), for solving large‐scale electromagnetic scattering problems in a rigorous and efficient manner. This parallel and iteration‐free technique, called CBFEM‐PO, decomposes the computational domain into a number of subdomains, and generates three types of characteristic basis functions (CBFs) that are specially‐tailored to each individual subdomain. Of these, the first two types of CBFs are comprised of primary and secondary bases arising from the self‐interactions in each subdomain and mutual‐couplings between different subdomains, respectively. They are obtained by solving the localized problem in each subdomain, isolated by PML regions. The third‐type of CBFs are derived by using the PO fields for different incident angles, polarization, and frequency. Two important salutary features of the proposed technique are: considerable reduction in the matrix size, which makes it feasible to use direct solvers; and convenient parallelizability that enables us to decrease the overall computation time by utilizing parallel platforms. We present a number of representative examples to illustrate the versatility of the method in solving 3D electromagnetic scattering problems. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1053–1060, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25134
Parallel coupled CPW filters for spurious band suppression
Authors: Fernández‐Prieto Armando , Martel Jesús , Medina Francisco , Mesa Francisco
Published: March 2010

Modified coplanar waveguide (CPW) edge‐coupled band‐pass filters with floating conductor strips printed below the coupled‐line sections are proposed. These structures allow one to suppress the first undesired spurious passband associated with the nonhomogeneous nature of the dielectric in CPW structures. Also, tight coupling levels can be easily achieved. An optimization code based on a fast quasi‐TEM solver is used to optimize the dimensions of the filter sections, in such a way that final dimensions are obtained in less than 1 min. A couple of filters have been built and measured to illustrate the theory. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1094–1097, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25135
A compact and low‐loss LTCC diplexer with high‐band selectivity and high isolation for dual‐band applications
Authors: Kim Tae Wan , Lee Young Chul
Published: March 2010

This article presents a compact and low‐loss diplexer for dual‐band applications using a LTCC (low temperature co‐fired ceramic) multilayer technology. This diplexer is composed of the high‐pass filter (HPF) and low‐pass filter (LPF) in order to separate GSM (global system for mobile) and CDMA (code division multiple access) band. For enhancing band selectivity of the diplexer, a shunt capacitor and inductor are designed in the HPF and LPF, respectively. In addition, a transmission zero is designed at the stopband of the LPF using a shunt inductor for improving isolation characteristics. The diplexer is realized in a 6‐layer LTCC substrate with a relative dielectric constant of 7. The size of the fabricated diplexer including CPW pads is 3.45 × 4.0 × 0.7 mm3. A measured insertion loss (IL) and return loss (RL) of the GSM band are less than −0.54 dB and −10.50 dB, respectively. In the case of CDMA band, the IL of −1.13 dB and RL of below −6.16 dB are archived. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1134–1137, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25137
Compact and wideband PIFA for DCS/PCS/UMTS/WLAN communication system
Authors: Pang Jiang‐Yi , Xiao Shao‐Qiu , Chen Shi‐Tao , Wang Bing‐Zhong
Published: March 2010

In this article, a compact and wideband planar inverted‐F antenna is introduced.The bandwidths for s11 < −10 dB are up to 790 MHz (a fractional bandwidth of 38.2%) with bending a part of metal radiator down and notching a rectangle slot. Measured results show that the designed antenna can meet the requirements of the DCS/PCS/UMTS/WLAN communication system. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1097–1100, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25138
Intrinsic and extrinsic fiber Fabry‐Perot sensors for acoustic detection in liquids
Authors: Lima S. E. U. , Frazão O. , Farias R.G. , Araújo F. M. , Ferreira L. A. , Miranda V. , Santos J. L.
Published: March 2010

This article reports the development of two sensing head configurations based on extrinsic and intrinsic fiber Fabry‐Pérot interferometers for the detection of incipient faults in oil‐filled power transformers. The performances of the sensing heads are characterized and compared with the situations where it operates in air, water, and oil and promising results are obtained, which will allow the industrial development of practical solutions. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1129–1134, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25139
A CPW‐fed wideband spiral slot antenna with circular polarization
Authors: Wang Chien‐Jen
Published: March 2010

A new design of broadband slot antenna with circular polarization is presented. The broadband characteristics are achieved using a coplanar‐waveguide (CPW)‐fed two‐arm spiral slot configuration. The spiral slot antenna and the feeding structure are fabricated on the same plane of the substrate so that the circuit process and the position alignment could be simplified. The improvement of circular polarization for the antenna is obtained mainly by an arc slot surrounding the spiral slots. The turn number of the spiral slots and the geometrical dimensions of the arc slot are varied in order to derive the better performance of the circular polarization. The measured impedance bandwidth of a S11< −10 dB ranges from 1.25 to 8 GHz and covers most of the commercial wireless communication systems, such as GPS, DCS, PCS, IMT‐2000, WLAN, and HiperLAN. The measured 3‐dB axial‐ratio bandwidth (ARBW) is 10.6% with respect to 1.605 GHz. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1204–1208, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.25142
Analytical design of a half‐mode substrate integrated waveguide Wilkinson power divider
Authors: Suntives A. , Smith N. A. , Abhari R.
Published: March 2010

This article presents a new approach in designing half‐mode substrate integrated waveguide Wilkinson power dividers based on analytical relations. Even‐ and odd‐mode analysis is used to determine the required value of the branch resistance and optimize the power divider performance, namely the output ports' isolation. In this manner, the design process for this microwave component is simplified and expedited, while an excellent correlation with full‐wave simulations is maintained. Measurements of the fabricated prototype corroborate the calculated results and demonstrate a wide output‐port isolation bandwidth of 71%. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1066–1069, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25145
Design of a broadband microstrip crossover for ultra‐wideband applications
Authors: Kusiek A. , Marynowski W. , Mazur J.
Published: March 2010

This article presents the investigations of ultra‐wideband microstrip crossover. In the design procedure, the equivalent circuit of microstrip crossover is used. To improve parameters of the investigated structure, two configurations of compensating circuits are designed and examined. The numerical results are experimentally verified. A good agreement between simulation results and measured ones is obtained. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1100–1104, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25146
Simplified design of multilayered substrate‐integrated waveguide Riblet–Saad couplers
Authors: Labay Vladimir A. , Bornemann Jens
Published: March 2010

A simplified design procedure for dual‐ and triple‐layered Riblet–Saad directional couplers in substrate‐integrated waveguide (SIW) technology is presented. Emphasis is placed on a design that considers ease of fabrication and includes interface ports such as microstrip‐to‐SIW transitions with straight, bent, and mitered microstrip lines. Designs are performed in an HFSS environment, which is verified by comparison with an independent field‐solver simulation. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1142–1144, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.25149
A compact DVB‐H Marchand balun using vertically coupling CPW structure
Authors: Lee Han Lim , Kim Dong‐Zo , Lim Won‐Gyu , Lee Moon‐Que , Yu Jong‐Won
Published: March 2010

A compact DVB‐H (digital video broadcasting—Handheld) Marchand balun using coplanar waveguide (CPW) coupling structure is presented.The proposed structure combines a double sided meandered CPW Marchand structure with lumped elements. Having the vertical coupling of meandered CPW Marchand structure, wide bandwidth for DVB‐H band (470–710 MHz) is achieved. Also, lumped elements are used to reduce the physical length of the coupling meandered lines. The proposed DVB‐H balun is fabricated on FR‐4 board and both simulated and measured results are presented to illustrate its performance. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1174–1177, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25150
Black Box Multigrid with coarsening by a factor of three
Authors: J. E. Dendy  , Moulton J. D.
Published: March 2010

Black Box Multigrid (BoxMG) is a robust variational multigrid solver for diffusion equations on logically structured grids. BoxMG standardly uses coarsening by a factor of two. It handles cell‐centered discretizations on logically rectangular grids by treating the cell‐centers as the unknowns to be coarsened. Such a strategy does not preserve the cell structure. That is, coarse‐grid cells are not the union of fine‐grid cells. In some applications, such as local grid refinement, it is desirable that the cell structure be preserved. In this paper, we develop a method that employs coarsening by a factor of three. It is a natural generalization of standard BoxMG, using operator‐induced interpolation (which approximately preserves the continuity of the normal flux), restriction as the transpose of interpolation, and Galerkin coarsening. In addition, we introduce a new colored block Gauss–Seidel scheme that is motivated by the form of the interpolation operator, dubbed ‘pattern’ relaxation. We present numerical results that demonstrate robustness of this method with respect to discontinuous diffusion coefficients, boundary conditions, and grid dimension. Published in 2010 by John Wiley & Sons, Ltd.
Flatness based trajectory planning for a semi‐linear hyperbolic system of first order p.d.e. modeling a tubular reactor
Authors: Woittennek Frank , Rudolph Joachim , Knüppel Torsten
Published: March 2010

Trajectory planning and open loop control design for semi‐linear hyperbolic systems in one space dimension is considered. A “flatness based” method is introduced on an example of a convection dominated tubular reactor with heat exchanger. More generally, the method applies to boundary value problems that can be translated into Cauchy problems w.r.t. the spatial coordinate. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Feedforward control design for a semilinear wave equation
Authors: Wagner Marc Oliver , Meurer Thomas , Kugi Andreas
Published: March 2010

This paper presents a flatness‐based approach for the solution of the feedforward control problem for a boundary controlled semilinear wave equation. The solution to a given piecewise analytical desired output trajectory is shown to be piecewise analytical, which allows the application of a formal power series approach on suitable subregions in adequate coordinates. The subregions are determined by the characteristic curves of the system passing through the non‐analyticity points of the desired trajectory. Convergence of the solution is demonstrated and simulation results are given for some set of parameters. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)