bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Cation Structure on the Mesophase Architecture of Self‐Assembled and Polymerized Imidazolium‐Based Ionic Liquids
Authors: Batra Dolly , Seifert Sönke , Firestone Millicent A.
Published: June 2007

The binary phase behavior of a series of imidazolium‐based ionic liquids (ILs) has been investigated. In particular, the effect of two structural modifications of the imidazolium cation, alkyl chain length, and the introduction of a polymerizable acryloyl group at the alkyl chain terminus, has been studied using small angle X‐ray scattering. Upon increasing water content, the non‐polymerizable IL, 1‐decyl‐3‐methylimidazolium chloride, adopts mesophase structures of predominately two‐dimensional (2D) hexagonal symmetry, including structures intermediate in character between lamellae and 2D hexagonal micelles. Introduction of a photopolymerizable acryloyl functional group to form 1‐(10‐(acryloyloxy)decyl)‐3‐methylimidazolium chloride produces a rod‐coil IL cation that yields self‐assembled mesophases in which the formation of tetragonal morphologies is favored. Covalent linking of the IL cations by UV‐induced polymerization converts the lyotropic mesophase into three‐dimensional biocontinuous chemical gels. Reducing the alkyl chain length, as in the polymerizable IL cation 1‐(8‐(acryloyloxy)octyl)‐3‐methylimidazolium chloride, severely reduces the self‐assembled mesophase order, and triggers the formation of only weakly ordered one‐dimensional lamellar structures.

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Reducing uninformed responses: The effects of product‐class familiarity and measuring brand knowledge on surveys
Authors: Graeff Timothy R.
Published: June 2007

Consumers often give answers to survey questions about which they are uninformed. Although research has documented this phenomenon and examined the conditions under which it occurs, the current research project is the first to examine how survey researchers might reduce uninformed response bias through the use of additional questions added to surveys that measure knowledge of brands for which consumers might be uninformed. In the current study, adding brand knowledge questions pertaining to an unknown (fictitious) brand reduced the likelihood of respondents providing uninformed responses when later asked to evaluate that brand. However, the effects of asking for brand familiarity on uninformed response rates differed by consumers' level of product‐class familiarity and the relative placement of the brand knowledge and brand attitude questions on the survey. Brand knowledge questions can suggest the existence of brands, placing them within a knowledge schema, thus leading to more uninformed responses from consumers low in product‐class familiarity. These results, coupled with recent other research findings suggest that researchers must consider the effects of related knowledge on what have been previously considered completely uninformed responses. © 2007 Wiley Periodicals, Inc.
Innovativeness, exploratory behavior, market mavenship, and opinion leadership: An empirical examination in the Asian context
Authors: Ruvio Ayalla , Shoham Aviv
Published: June 2007

The market maven construct, developed by Feick and Price (1987), has been used in empirical studies in the USA, South Africa, Germany, Poland, and Hungary. This study extends previous research by being the first to use the general mavenship concept in an Asian country (Israel). Furthermore, the study examines market mavenship and opinion leadership as outcome concepts arising from exploratory behavior or innovativeness tendencies. Additionally, the impact of a three‐dimensional exploratory behavior concept is compared to the impact of a unidimensional innovativeness concept on opinion leadership and market mavenship. Structural Equation Modeling (SEM) was used to test the two nomological models based on a sample of 142 adult Israeli consumers. Although both exploratory behavior and innovativeness affect market mavenship and opinion leadership, the impact of the former is stronger. Additionally, the impact of the “new brand trial” facet of exploratory behavior on market maven was comparable to that of innovativeness, whereas its impact on opinion leadership was weaker than the impact of innovativeness. © 2007 Wiley Periodicals, Inc.
Guilt appeals: Persuasion knowledge and charitable giving
Authors: Hibbert Sally , Smith Andrew , Davies Andrea , Ireland Fiona
Published: June 2007

This paper applies the persuasion knowledge model to explain consumers' responses to charity guilt appeals. With data obtained through a stimuli‐driven survey, the research examines the relationships between knowledge of persuasion tactics and charities, and the level of felt guilt experienced in response to an advertisement and subsequent donation intentions. The findings show that guilt arousal is positively related to donation intention, and that persuasion and agent knowledge impact the extent of guilt aroused. The research confirms that consumers are active rather than passive processors of marketing communications by revealing the role of persuasion and agent knowledge as methods of coping with and informing responses to guilt appeals. Specifically, the research finds that manipulative intent and the respondents' skepticism toward advertising tactics in general are negatively related to guilt arousal but that their affective evaluation and beliefs about a charity are positively related to feelings of guilt. However, it also shows that there is a positive direct relationship between perceived manipulative intent and the intention to donate. © 2007 Wiley Periodicals, Inc.
Transport of Guest Molecules by Unimolecular Micelles Evidenced in Analytical Ultracentrifugation Experiments
Authors: Rasa Mircea , Meier Michael A. R. , Schubert Ulrich S.
Published: June 2007

The ability of star‐shaped, block copolymer‐based unimolecular micelles to encapsulate and transport guest molecules was studied. Analytical ultracentrifugation studies clearly showed that methyl‐orange guest molecules could be encapsulated and transported, together with unimolecular micelles consisting of 5‐arm, star‐shaped block copolymers with a poly(ethylene glycol) core and a poly(ε‐caprolactone) corona. Sedimentation‐velocity and equilibrium measurements were performed to determine the sedimentation coefficients, molar masses, and diffusion coefficients of the loaded, unimolecular micelles. It was observed that the transport of guest molecules by unimolecular micelles was a function of the molecular weight of the star‐shaped block copolymers and therefore also of their size.

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Universal Methodology for Block Copolymer Synthesis
Authors: Bellas Vasilios , Rehahn Matthias
Published: June 2007

Chemoselective stepwise coupling between living polymers and a heterobifunctional linking agent is shown to be a versatile, facile, and efficient methodology for block copolymer synthesis. This protocol is based on the quantitative formation of the end‐functionalized precursor in the first coupling step. In this proof‐of‐concept study, we investigate the behavior of specific macroanions, prepared through living anionic polymerization (LAP). Nevertheless, the applicability range is becoming exceptionally wide upon transformation reactions, e.g., by tailoring the chain‐termini nucleophilicity via endcapping. This novel protocol will considerably expand the limits of LAP, rendering viable the construction of advanced and tailor‐made materials via an effortless pathway.

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Development of Nanodomain and Fractal Morphologies in Solvent Annealed Block Copolymer Thin Films
Authors: Peng Juan , Han Yanchun , Knoll Wolfgang , Kim Dong Ha
Published: June 2007

We have systematically studied the thin film morphologies of asymmetric polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) diblock copolymer subjected to solvent vapors of varying selectivity for the constituent blocks. Upon a short treatment in neutral or PS‐selective vapor, the film exhibited a highly ordered array of hexagonally packed, cylindrical microdomains. In the case of PEO selective vapor annealing, such ordered cylindrical microdomains were not obtained. Instead, fractal patterns on the microscale were observed and their growth processes investigated. Furthermore, hierarchical structures could be obtained if the fractal pattern was exposed to neutral or PS selective vapor.

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Increasing the wear resistance of stainless steels
Authors: Berns H.
Published: June 2007

The wear resistance of martensitic, austenitic and duplex stainless steels is increased by carbon and nitrogen in solid solution and in addition by carbides and nitrides, which are formed during conventional ingot metallurgy or by powder metallurgical processing. High temperature and low temperature nitriding provide a hard surface zone. Characteristic alloys and applications are discussed, which try to optimize the resistance to wear and corrosion.
Strangpressen von verschleißbeständigen Fe‐Basis MMC
Authors: Karlsohn M. , Theisen W.
Published: June 2007

Steigende Anforderungen an technische Oberflächen, die sowohl thermisch, korrosiv, verschleißend oder durch eine Kombination dieser Beanspruchungsarten geprägt sein können, schieben die Entwicklung von maßgeschneiderten Werkstoffen oder Beschichtungen an. Wird die Beanspruchung der Oberfläche durch abrasiven Verschleiß dominiert, so bietet die Pulvermetallurgie optimale Möglichkeiten einer beanspruchungsgerechten Werkstoffauslegung. Neben der Wahl der Metallmatrix (MM, meist Fe‐, Ni‐ oder Co‐Basis) ist eine abgestimmte Hartstoffzugabe (HS), z. B. durch Karbide, Nitride, Boride oder Oxide möglich, die zusätzlich durch eine in weiten Bereichen mögliche Variation von Art, Form, Partikelgröße und Volumenanteil des Hartstoffs gekennzeichnet ist. Das bislang dominierende Herstellungsverfahren für solche Bauteile ist das Heiß‐Isostatische‐Pressen (HIP), welches zu dichten Gefügen führt, aber aufgrund der aufwändigen, weil konturnahen Kapseltechnik, hohe Herstellungskosten verursacht. Deshalb wurde im Rahmen eines DFG‐Projektes das direkte Warmstrangpressen von zylindrischen Pulverkapseln mit MMC auf Fe‐Basis zur Herstellung von verschleißbeständigen Langprodukten untersucht. Zur Steigerung des Verschleißwiderstandes wurden den härtbaren Stahlmatrices Wolframschmelz‐ oder Titankarbid in unterschiedlichen Volumengehalten zugesetzt. Die stranggepressten Werkstoffe wurden bezüglich ihrer Verdichtung und Gefügeausbildung, ihre Biegebruchfestigkeiten und ihres Verschleißwiderstandes untersucht.
Detonationsflammspritzen hartstoffhaltiger Funktionsschichten
Authors: Tillmann W. , Vogli E. , Nebel J.
Published: June 2007

Die Möglichkeiten zur Verbesserung der Oberflächeneigenschaften mittels thermischer Spritzverfahren sind seit langer Zeit bekannt. Je nach Zielsetzung lassen sich durch die Beschichtung unterschiedliche Eigenschaften, wie elektrische Leitfähigkeit, Isolation, hohe Verschleißbeständigkeit oder Korrosionsschutz erreichen. Die nachfolgend beschriebenen Versuche zeigen, dass thermische Spritzverfahren ebenfalls eine Verfahrensalternative zu aufwändigen und stark einschränkenden Sinter‐ und Lötprozessen bei der Herstellung von Schleifwerkzeugen für die Gesteinsbearbeitung darstellen können. So ist basierend auf dem Verfahren des Detonationsflammenspritzens eine Fabrikationsmethode dargestellt, große superabrasive Partikel in eine metallische Matrix einzubinden, um damit die Vorraussetzung zu schaffen, Schleifwerkzeuge kostengünstig, mit hoher Geometrievariabilität und Flexibilität herzustellen. Zur Verifikation der Prozesseignung wurden im Rahmen dieser Forschungsarbeit die Schichtmorphologie, Hartpartikelverteilung und die Bindungsqualität in Bezug auf das Anforderungsprofil bewertet. Zusätzlich wurde der Einfluss der Prozesstemperatur und der Substrattemperatur auf die Eigenschaften des MMC‐Verbundes untersucht.
Laserstrahlschweißen von Mikrodrähten aus Nickel‐Titan‐Formgedächtnislegierungen und austenitischem Stahl
Authors: Gugel H. , Theisen W.
Published: June 2007

Die besonderen Eigenschaften von Nickel‐Titan Formgedächtnislegierungen finden derzeit Anwendung in der Mikrosystem‐ und in der Medizintechnik. Um Nickel‐Titan Komponenten in bestehende Baugruppen zu integrieren, müssen sie oft mit anderen Materialien verbunden werden. In diesem Beitrag geht es daher um das Laserstrahlschweißen dünner pseudoelastischer Nickel‐Titan‐Drähte (Ø 100μm) unter Verwendung eines Neodym‐dotierten Yttrium Aluminium Granat Lasers. Auf der Basis umfangreicher Parameterstudien gelang es fehlerfreie Verbindungen herzustellen, die hier im Nachgang mit Blick auf die Gefüge in der Schmelz‐ und Wärmeeinflusszone, das Verhalten im statischen Zugversuch und mit Blick auf die strukturelle Ermüdung untersucht wurden. Es kann gezeigt werden, dass artgleiche Nickel‐Titan‐Verbindungen etwa 75 % der Bruchfestigkeit reiner Nickel‐Titan Drähte erreichen. Bei der Verschweißung von Nickel‐Titan mit Stahl wurde keine Zwischenschicht verwendet. Diese artungleichen Nickel‐Titan/Stahl‐Verbindungen zeigen Festigkeiten in der Schmelz‐ und Wärmeeinflusszone, die oberhalb der Plateauspannung liegen, so dass die pseudoelastischen Eigenschaften auch im Verbund mit Stahl genutzt werden können.
Deep brain stimulation in Tourette's syndrome
Authors: Bajwa Rizma Jalees , de Lotbinière Alain J. , King Robert A. , Jabbari Bahman , Quatrano Susan , Kunze Kimberly , Scahill Lawrence , Leckman James F.
Published: June 2007

A 48‐year‐old man with severe, lifelong Tourette's syndrome (TS) characterized by forceful self‐injurious motor tics and obsessive‐compulsive disorder was treated with bilateral deep brain stimulation (DBS). The decision to treat was based on his progressive neurological impairment (left sided weakness secondary to spinal cord injury) because of his relentless, violent head jerks. Electrodes were implanted at the level of the medial part of the thalamus (centromedian nucleus, the substantia periventricularis, and the nucleus ventro‐oralis internus). DBS resulted in a substantial reduction of tics. These data show that bilateral DBS of the thalamus can have a good effect on severe tics in adult patients suffering from intractable TS. © 2007 Movement Disorder Society
Pathological gambling in Parkinson's disease: Risk factors and differences from dopamine dysregulation. An analysis of published case series
Authors: Gallagher David A. , O'Sullivan Sean S. , Evans Andrew H. , Lees Andrew J. , Schrag Anette
Published: June 2007

Pathological gambling (PG) has been reported as a complication of the treatment of Parkinson's disease (PD). We examined all published cases of PG for prevalence and risk factors of this complication, the relationship of PG and use of dopamine agonists (DA), and the relationship of PG to the dopamine dysregulation syndrome (DDS). The prevalence of PG in prospective studies of PD patients using DA has been reported between 2.3 and 8%, compared to approximately 1% in the general population. As in the general population, PD patients with this complication are often young, male and have psychiatric co‐morbidity. The vast majority are on DA, often at maximum dose or above. Differences between oral DA failed to reach significance. PG associated with levodopa monotherapy is uncommon, but in the majority of cases levodopa is co‐prescribed, suggesting possible cross‐sensitization of brain systems mediating reward. PG can occur with DDS but often occurs in isolation. In contrast to DDS, escalation and self regulation of anti‐parkinsonian medication are not usually seen. PG in patients with PD using DA is higher than PG reported in the general population, but shares similar characteristics and risk factors. PG is predominantly associated with oral DA. It often occurs in isolation and may not be associated with DDS, which typically occurs on treatment with levodopa or subcutaneous apomorphine. © 2007 Movement Disorder Society
Diffusion weighted imaging best discriminates PD from MSA‐P: A comparison with tilt table testing and heart MIBG scintigraphy
Authors: Köllensperger Martin , Seppi Klaus , Liener Claudia , Boesch Sylvia , Heute Dirk , Mair Katherina J. , Mueller Joerg , Sawires Martin , Scherfler Christoph , Schocke Michael F. , DonnemilIer Eveline , Virgolini Irene , Wenning Gregor K. , Poewe Werner
Published: June 2007

Both diffusion weighted magnetic resonance imaging (DWI) of the basal ganglia and meta‐iodobenzylguanidin (MIBG) scintigraphy of the heart have been reported useful in the differential diagnosis of patients with Parkinson's disease (PD) vs. the parkinson variant of multiple system atrophy (MSA‐P). Their diagnostic value, however, has never been directly compared in patients with parkinsonism and autonomic dysfunction. We have studied 9 patients with PD and 9 patients with MSA‐P matched for age and disease severity. Regional trace of the diffusion tensor values were determined in the putamina. Cardiac MIBG uptake was quantified by comparing regions of interest over heart and mediastinum Heart/Mediastinum (H/M) ratio. Furthermore, all patients underwent tilt testing. PD patients showed significantly lower H/M ratios than normal controls; however, there was considerable overlap between the two patient groups. We did not detect any significant differences of blood pressure response to passive tilt between the two patient groups. Sensitivity of MIBG scintigraphy versus DWI for the differentiation of MSA‐P from PD was 55.6% vs. 100%, specificity 88.8% vs. 100%, and area under the curve 0.802 vs. 1.000. Our data suggest that DWI is superior to both tilt table testing and MIBG scintigraphy in the differential diagnosis of PD versus MSA‐P. © 2007 Movement Disorder Society
Tardive dyskinesia in children treated with atypical antipsychotic medications
Authors: Wonodi Ikwunga , Reeves Gloria , Carmichael Dana , Verovsky Ilene , Avila Matthew T. , Elliott Amie , Hong L. Elliot , Adami Helene M. , Thaker Gunvant K.
Published: June 2007

Recent years have witnessed increased antipsychotic treatment of children despite limited long‐term safety data in children. In this study, motor side effects associated with the use of antipsychotic drugs in children were examined in a sample of pediatric psychiatric patients. Child and adolescent psychiatric patients receiving antipsychotics (most were on atypicals) for 6 months or longer (n = 118) were compared with antipsychotic‐naïve patients (n = 80) with similar age, sex ratio, and diagnoses. Only 19% of patients on antipsychotics had ever experienced psychotic symptoms. Eleven children (9%) on antipsychotics exhibited dyskinesia, when compared with 0 in the naïve group (P = 0.003, Fisher's exact test). Nine of 62 African–American children (15%) on antipsychotics exhibited dyskinesia, when compared with only 4% (2 of 52) of European–American children (P = 0.003, Fisher's exact test). Children treated with antipsychotic drugs might experience a significant risk of dyskinesia even when treated only with atypical antipsychotics. Ethnicity might also be a risk factor for dyskinesia in children. Side‐effect profile of the atypical antipsychotic drugs in children may be much different than that in adults. © 2007 Movement Disorder Society
Rhythmic movements in idiopathic REM sleep behavior disorder
Authors: Manni Raffaele , Terzaghi Michele
Published: June 2007

Reported are two cases of video‐PSG captured head‐rolling occurring, in the context of REM Sleep Behavior Disorder (RBD) episodes, in two patients affected with idiopathic RBD and without past personal or familiar history of Rhythmic Movement Disorder during sleep. It has been speculated that the activation of neuronal pathways which underlie REM‐related loss of motor control in RBD, may involve the Central Pattern Generator neuronal networks leading to the induction of Rhythmic Movements during RBD episodes, thereby allowing the re‐emergence, in pathological conditions in later life, of a motor behavior typically seen in the early stage of life. © 2007 Movement Disorder Society
Restless legs syndrome in Parkinson's disease
Authors: Gómez‐Esteban Juan C. , Zarranz Juan J. , Tijero Beatriz , Velasco Fernando , Barcena Joseba , Rouco Idoia , Lezcano Elena , Lachen María C. , Jauregui Amaia , Ugarte Amaia
Published: June 2007

The present study explores the frequency of RLS in PD and focuses on the clinical differences between patients with and without restless legs syndrome (RLS). A cross‐sectional study was designed, comprising 114 patients diagnosed with PD. Those patients positive for RLS were assessed for intensity of the syndrome (IRLS). We compared the clinical characteristics of the patients with and without RLS, using specific scales: Unified Parkinson's Disease Rating Scale (UPDRS I‐IV), quality of life (Parkinson's Disease Questionnaire, PDQ 39), sleep symptoms (Parkinson's Disease Sleep Scale, PDSS), and diurnal hypersomnia (Epworth Sleepiness Scale). Twenty‐five patients (21.9%) out of a total of 114 subjects diagnosed with PD met the RLS diagnostic criteria. RLS was more frequent in women (68%). The patients with RLS showed poorer scores on the PDSS (PD‐RLS+: 102.4 ± 15.1 vs PD‐RLS‐: 113.2 ± 16.4) (P = 0.005) and in the bodily discomfort dimension of the PDQ‐39 (PD‐RLS+ 6.1 ± 3.4 vs PD‐RLS‐ 3.8 ± 2.6) (P = 0.002). Analysis of the subscales of the PDSS showed significant differences (P < 0.001) between both groups of patients in items 4 and 10, and to a lesser degree in items 5 (P = 0.01) and 11 (P = 0.02) There was no increased incidence of diurnal hypersomnia in the group of patients with RLS. There were no differences in the rest of the variables. RLS is frequent in patients with PD, though this condition doesn't apparently affect quality of life or lead to an increased presence of diurnal hypersomnia. It would be advisable to validate the diagnostic criteria of RLS in this specific group of patients. © 2007 Movement Disorder Society
High levels of equol in organic skimmed Finnish cow milk
Authors: Hoikkala Antti , Mustonen Eeva , Saastamoinen Ilkka , Jokela Tuija , Taponen Juhani , Saloniemi Hannu , Wähälä Kristiina
Published: June 2007

The isoflavonoids, equol, formononetin, daidzein, genistein, biochanin A, and O‐demethylangolensin (O‐DMA), were analyzed from commercial cartons of skimmed Finnish milk by HPLC‐diode array detector (DAD)‐FL. We found 411 ± 65 ng/mL of equol and traces of formononetin and daidzein in organic skimmed milk whereas conventionally produced milk contained 62 ± 16 ng/mL of equol and no formononetin or daidzein.
Dispersion properties of circular dielectric waveguides loaded with periodic metal disks
Authors: Lai Chin‐Jui , Hsu Chung‐I. G. , Lee Ching‐Her , Kiang Jean‐Fu
Published: June 2007

The dispersion properties of a circular dielectric waveguides loaded at the center with periodic center‐protruded metal disks were investigated using a mode‐matching technique in conjunction with the Floquet theorem. The metal disks with rectangular and crisscrossed cross‐sectional shapes in the longitudinal direction were considered. The effects of the cylinder radius, disk size, and disk spacing on the dispersion curves plotted in the form of the Brillouin diagram were studied. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2057–2061, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22645
Microstrip array antenna for fire‐detection applications
Authors: Vincetti L. , Polemi A. , Zoboli M.
Published: June 2007

In this paper, a first investigation on critical issues for a fire‐detection ground‐based Ku‐band radiometer antenna design is addressed. A printed technology with standard dielectrics has been employed, to reach low cost, simplicity in realization, and easy integrability with the electronic front‐end. The antenna has been designed as an array of patches, where number of elements, spacings, and feeding currents has been optimized to fulfill requirements of low side lobe level and good crosspolarization. For the radio frequency front‐end, the receiver architecture is a direct‐conversion topology, because it is well suited to be monolithically integrated in a single chip. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2279–2282, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22649
Multiwavelength Raman fiber laser inserting a sampled chirped fiber Bragg grating
Authors: Ning G. , Shum P. , Zhou J. Q. , Xia L.
Published: June 2007

A simple multiwavelength Raman fiber ring laser with equalized peak power is proposed and demonstrated experimentally by inserting a sample chirped fiber Bragg grating. By adjusting the polarization controller (PC) in the ring cavity, up to ten stable wavelengths with equalized peak power are achieved at room temperature. The Raman fiber ring laser has many advantages such as simple structure, low loss, and multiwavelength lines with moderate output power. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2242–2245, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22652
A 1.5‐V 0.25‐μm CMOS up‐converter for 3–5 GHz low‐power WPANs
Authors: Sapone Giuseppina , Palmisano Giuseppe
Published: June 2007

In this article, the measured performance of a 3–5 GHz low‐power up‐converter is presented. The circuit is based on a current‐reuse topology with resistive load. It was implemented in a standard low‐cost 0.25‐μm CMOS technology. The up‐converter achieves a 3.8‐dB power gain, an output 1‐dB compression point of −10.8 dBm, and a 8‐dB single‐sideband noise figure, while drawing only 2.3 mA from a 1.5‐V supply voltage. An operating bandwidth of 1.5 GHz was measured. The proposed circuit complies with the wideband/low‐power requirements of 3–5 GHz ultrawideband WPANs. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2209–2212, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22654
Tunable (Ba, Sr)TiO3 interdigital capacitor onto Si wafer for reconfigurable radio
Authors: Kim Ki‐Byoung , Tae‐Soon Yun  , Lee Jong‐Chul , Chaker Mohamed , Wu Ke
Published: June 2007

In this article, the potential feasibility of integrating BST films into Si wafer by adopting tunable interdigital capacitor (IDC) with TiO2 thin film buffer layer is suggested. TiO2 as buffer layer is grown onto Si substrate by atomic layer deposition and the coplanar IDC on BaxSr1−xTiO3(500 nm)/TiO2(50 nm)/high resistivity Si (HR‐Si) is fabricated. BST interdigital tunable capacitors integrated on HR‐Si substrate with high tunability and low loss tangent are characterized for their microwave performances. BST/HR‐Si and BST/TiO2/HR‐Si IDCs show much enhanced tunability values of 31% and 40%, respectively as compared to the value of 21% obtained with BST film on MgO single crystal substrate at the bias of 5 kV/cm. BST/TiO2/HR‐Si structure shows much improved figure of merit of 504.4 as compared to 418.53 and 101.68 of BST/MgO and BST/HR‐Si structure, respectively. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2144–2148, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22657
Application of metamaterial unit cell in bandpass filter
Authors: Jiusheng Li , Tieying Du
Published: June 2007

Using microstrip technology, a novel metamaterial unit cell is presented. The metamaterial unit cell consists of microstrip gaps and via hole whose behavior is equivalent to the combination of series capacitors and shunt inductors, respectively. A new chamfered band structure bandpass filter is designed and fabricated using the presented metamaterial unit cell. The transmission loss S21 and return losses S11 of the proposed bandpass filter are equal to −0.41 and −25.5 dB, respectively. The experimental and simulation results closely correspond to each other. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2109–2111, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22659
Printable Yagi antenna with closely spaced elements
Authors: Lim Sungkyun , Ling Hao
Published: June 2007

A two‐element, planar Yagi antenna with closely spaced elements is reported. Multiple folding in the driver is used to boost up the low radiation resistance due to the close spacing between the driver and the director. The antenna dimensions are first optimized in wire form and then transferred into a printed version on PET film. A prototype planar monopole Yagi is built and measured at 1 GHz. The maximum realized gain of the antenna on 50‐μm PET film is measured to be 9.56 dB. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2106–2109, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22660
Miniature wideband filter based on coupled‐line sections and quasi‐lumped element resonator
Authors: Zhurbenko Vitaliy , Krozer Viktor , Meincke Peter
Published: June 2007

A new design of a wideband bandpass filter is proposed, based on coupled‐line sections and quasi‐lumped element resonator, taking advantage of the last one to introduce two transmission zeros and suppress a spurious response. The proposed filter demonstrates significantly improved characteristics in comparison with traditional coupled‐line filter and exhibits a very compact structure. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2076–2079, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22661
A novel switchable lowpass filter constructed with electromagnetic bandgap and illumination‐sensitive cadmium sulfide
Authors: Wu Jack , Qiu S. N. , Qiu C. X. , Shih I.
Published: June 2007

A novel construction of microwave switchable lowpass filter based on electromagnetic bandgap (EBG) and cadmium sulfide (CdS) thin film is proposed. Linearly tapered slot‐array EBG structure is well known for its exceptional stopband ability and compact physical size. When the illumination‐sensitive CdS thin film is deposited on the perforations of the EBG structure, the stopband phenomenon induced by tapered slot‐array can be controlled by optical means. Innovative “conductive islands” were introduced to reside in the center of each perforation in order to enhance the optical switching. It has been demonstrated in both simulation and experimental measurement that the transmission coefficient is switched from 31.3 to 5.6 dB at 13 GHz when the gap width between the conductive island and the perforation is 30 μm. As the gap width decreases, the insertion loss can be reduced. Simulation result indicates that the insertion loss can be improved to around 1 dB at 13 GHz when the gap width is decreased to 5 μm. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2238–2242, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22665
Dual‐band planar rectangular ring microwave bandpass filter using high permittivity substrate
Authors: Hsu Cheng‐Hsing , Lin Chia‐Hsien , Huang Sen‐Hung , Hsu Chung‐I G. , Yu Cheng‐Chi , Tung Hsin‐Han
Published: June 2007

Dual‐band planar bandpass filter, using two microstrip rectangular ring resonators, is proposed for wireless LAN system such as IEEE 802.11 systems (2.4 or 5 GHz). The miniaturized bandpass filter is implemented using a high permittivity dielectric substrate. The full‐wave simulator IE3D is used to design the two coupled rectangular ring resonators. The responses of the implemented filter using Zr0.8Sn0.2TiO4 (εr = 37, tan δ = 0.00012) dielectric substrates are designed at dual‐band frequencies of 2.35 and 4.7 GHz. The compacted size and good agreement have been obtained between simulations and implementation results. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2236–2238, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22677
Ultrawideband aperture‐coupled vertical microstrip transition
Authors: Abbosh A. M.
Published: June 2007

Simple design guidelines for an ultrawideband aperture‐coupled vertical microstrip–microstrip transition are presented. The proposed transition utilizes broadside coupling between elliptical‐shaped microstrip patches at the top and bottom layers via an elliptical‐shaped slot in the ground plane, which is located at the mid layer. The simulated and measured results show that the proposed transition has less than 0.75 dB insertion loss and more than 13 dB return loss across the frequency band 3.1–10.6 GHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2207–2209, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22667
Effect of Li/Nb ratio on holographic storage properties of In:LiNbO3 crystals
Authors: Nie Yiran , Wang Rui , Wang Biao
Published: June 2007

In:LiNbO3 crystals with different Li/Nb ratios in the melts (Li/Nb = 0.94, 1.0, 1.1, 1.2) have been grown. The changes of the crystal structure on the Li/Nb were analyzed by the ultraviolet–visible absorption spectra. The holographic storage properties of In:LiNbO3 crystals were investigated by two‐wave coupling technique. The diffraction efficiency, response time, and photoconductivity of the crystals were measured. With increase in the ratio of Li/Nb, the diffraction efficiency decreases, the response time shortens, and the photoconductivity increases. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2169–2171, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22669
Novel dual‐broadband design of semicircular slot antenna for wireless communication
Authors: Hsiao Hai‐Ming , Lu Jui‐Han , Wu Jeun‐Wen
Published: June 2007

A novel design of semicircular slot antenna with dual‐broadband operation for 2.4/5 GHz wireless local network area (WLAN) is proposed. With the use of an arc‐shaped strip inset along the circle edge of the semicircular slot antenna, a new resonant mode close to the second operating mode of the regular semicircular slot antenna is excited to enhance the operating bandwidth of the high band, and the obtained impedance bandwidths for two operating bands can reach about 14.8% for 2.4 GHz band and 22.0% for 5 GHz band, which cover the required bandwidths of IEEE 802.11b/g (2.4–2.484 GHz) and IEEE 802.11a (5.150–5.950 GHz). The measured peak antenna gains for the operating frequencies across dual WLAN bands are measured to be, respectively, 4.7 and 4.9 dBi with the gain variations within 0.5 dBi. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2165–2169, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22670
Investigation of macrobending losses of standard single mode fiber with small bend radii
Authors: Wang Pengfei , Wang Qian , Farrell Gerald , Rajan Ginu , Freir Thomas , Cassidy John
Published: June 2007

An investigation of macrobending loss characteristics of a standard single mode fiber (SMF28) for small bend radii is presented theoretically and experimentally, which includes the bend loss of the SMF28 with coating layers and the bare SMF28 after stripping the coating layers and chemical etching of partial cladding. The significant influence of reflection occurring at the interface between the cladding and coating layer or the cladding layer and air on the bend loss is investigated theoretically and experimentally. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2133–2138, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22671
Chromatic dispersion effect on microwave photonic filter with a tunable linearly chirped fiber Bragg grating
Authors: Ning G. , Shum P. , Zhou Junqiang
Published: June 2007

Chromatic dispersion effect on a bandpass microwave photonic filter is presented using a tunable linearly chirped fiber Bragg grating (LCFBG). The 3‐dB bandwidth of the LCFBG is shifted nonlinearly with fixed centre wavelength to change its chromatic dispersion value. The bandpass notch filter is free from optically coherent interference and phase noise because of the two orthogonal axes of the Hi‐Bi fiber. Measured results agree with theoretical analysis. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2131–2133, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22672
Computation and optimization of resonant frequency and input impedance of a coax‐fed circular patch microstrip antenna
Authors: Gürel Çiğdem Seçkin , Aydın Elif , Yazgan Erdem
Published: June 2007

Microstrip antennas are important elements of today's wireless communication networks. In their various applications, it is critical to provide wide band operation around the resonant frequency providing good impedance match between the antenna element and the feed. In this study, new, simple, and accurate computation of resonant frequency and input impedance of double‐layered, coaxial fed circular disk microstrip antenna with air gap is performed. In the analysis, new effective radius and permittivity expressions are used in simple and modified form including modal effects. Then, a new approach is proposed to provide input impedance matching at resonant frequency via the application of microgenetic algorithm for wide band operation. The accuracy of theoretical calculations and impedance matching approach are presented for various structural parameters and operational modes of the antenna. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2263–2267, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22675
Accurate evaluation of singular potential integrals in an asymptotic‐phase method of moments formulation
Authors: Araújo M. G. , Taboada J. M. , Rodríguez J. L. , Obelleiro F.
Published: June 2007

The Khayat‐Wilton singularity cancellation technique has been adapted for computing the potential integrals involving the 3D Green's function and the linearly‐phased Rao‐Wilton‐Glisson (LP‐RWG) basis functions. The LP‐RWG basis functions are used to expand the induced currents in terms of current‐modes, which allows an efficient representation of the currents in large scatters using a fewer number of unknowns. The proposed procedure overcomes some drawbacks of other singularity schemes, such as the dependence of the triangular‐patch shape and the location of the observation points. In this sense, the proposed procedure is valid for singularities and “near” singularities on arbitrarily‐shaped triangular meshes. This significantly improves the reliability of the method of moments and related approaches in combination with the asymptotic phase formulation when dealing with arbitrary and automatically generated surface meshes. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2189–2197, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22680
Frequency‐tuned ultra wideband antenna with partial‐circular patch
Authors: Zhang Jingyun , Zhang Wenmei , Chen Xue , Gao Liping H. J.
Published: June 2007

A novel frequency‐adjustable ultra wideband antenna with coplanar waveguide‐fed is proposed and the design formula is presented. The optimized antenna presents 6.7:1 ratio bandwidth and 148% impedance bandwidth for the return loss less than −10 dB. The bandwidth can be changed through adjusting the slice of partial‐circular patch. Also, the numerical sensitivity analysis for different dimensions has been done. Good agreement between the measurement and simulation has been achieved. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2128–2131, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22683
Design of a novel HTS open‐loop SIR filter with the relocation of its second passband
Authors: Jin Shichao , Wei Bin , Zhang Xiaoping , Cao Bisong , Guo Xubo , Peng Huili , Gao Longma , Gao Baoxin
Published: June 2007

This paper presents a novel open‐loop stepped impedance resonator (OLSIR), which has advantage of compact structure and its relocatable first spurious frequency. A four‐pole high temperature superconducting (HTS) filter made up of OLSIRs is designed and fabricated'and the measurement result has good agreement with the simulation. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2097–2101, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22685
Modeling, optimization, and experimental evaluation of remotely pumped double‐pass EDFA
Authors: Hossain Nadir , Naji A. W. , Mishra V. , Abbou F. M. , Al‐Mansoori M. H. , Mahdi M. A. , Faidz A. R.
Published: June 2007

A simple rate equation model of double pass (DP) Erbium‐doped fiber amplifier (EDFA) is developed based on the Giles and Desurvire (1991) model of single pass (SP) EDFA. The mathematical equations to calculate stimulated absorption and emission rate between levels 1 and 2 of SP EDFA are modified by integrating the reflected backward propagating signal of DP EDFA. Reflection loss of signal by the reflector is included with the backward propagating signal of DP EDFA. The design parameters of DP EDFA are optimized using numerical simulation of the developed DP EDFA rate equation model to design remotely pumped optimized DP EDFA. Robustness and stability of the developed DP EDFA rate equation model are shown by analyzing the numerical results and output shapes, using various design parameters of DP EDFA. Finally, the developed DP EDFA rate equation model is validated with the help of experimental results. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2257–2261, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22687
Finline tapers using closed‐form expressions for millimeter wave integrated systems
Authors: Mittal Ashok , De Asok
Published: June 2007

Conventional techniques for designing waveguide‐to‐finline taper transitions are based on the design of a suitable impedance transformation profile used for pure TEM lines. Change of finline/slotline gap not only causes change in impedance but also correspondingly change in propagation constant. Thus the existing analysis, used for purely TEM lines, is inadequate in dealing with finline tapers. Analysis has also been carried out by varying the propagation constant using closed‐form expressions. Comparison of various taper profiles has been presented in this paper. Further in the present work, the width of the finline contour itself has been varied according to the function profiles as exponential, parabolic, cosine, and cosine squared forming the tapers. Broadband tapered transition from rectangular waveguide to offset slot asymmetric finline has been realized by gradually increasing the slot width using exponential taper profile. The designed asymmetric finline taper (two transition with one lambda spacing) using impedance variation with width exponential profile showed a very good result of 0.15–0.25 dB in the entire Ka‐band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2254–2257, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22688
Tailoring of the subwavelength focus
Authors: Sydoruk O. , Shamonina E. , Solymar L.
Published: June 2007

Subwavelength focusing by an ensemble of magnetically coupled metamaterial elements is studied theoretically for the case when all the dimensions are small relative to the electromagnetic wavelength. It is shown that in contrast to expectation a focus can be placed in any desired position for any transmitter‐lens configuration by the appropriate tuning of the receiver. A mathematical proof is provided and two examples are shown demonstrating a focal width of λ/60. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2228–2231, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22689
New set of 3D orthogonal edge basis functions for the vector wave equation solution
Authors: Gonçalves Marcos S. , Hernandez‐Figueroa Hugo E. , Bordonalli Aldário C.
Published: June 2007

New three‐dimension orthogonal basis functions for finite element solution of the vectorial wave equation are presented. These functions, based on the Whitney's edge elements, maintain the same properties as those of conventional basis functions, naturally generating diagonal matrices and enhancing numerical performance. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2224–2228, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22690
A novel spiral high impedance surface structure for size reduction
Authors: Lin Bao‐Qin , Zheng Qiu‐Rong , Yuan Nai‐Chang
Published: June 2007

A novel electromagnetic Band‐Gap (EBG) scheme is presented for size reduction. The proposed structure can be considered as one kind of distorted Sievenpiper High Impedance Surface (HIS) in a spiral shape, while it becomes extremely compact in size. Its design is detailed in this study, and two experimental results are presented. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2186–2189, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22691
The small UWB hybrid antenna
Authors: Chan Yi‐Wah , Luk Kwai‐Man
Published: June 2007

A small size end‐fire mode hybrid monopole/DR antenna is introduced and tested. The hybrid antenna combines an annular DRA and a quarter‐wave monopole antenna to perform ultrawideband response. The proposed technique is used to reduce the length of monopole antenna and improve the whole impedance bandwidth. The maximum gain and impedance bandwidth is 5.5 dBi and 100% (VSWR ≤ 2), respectively. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2157–2159, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22693
Compact ultra‐wideband bandpass filter using uniplanar compact photonic bandgap structure
Authors: Baik J. W. , Hyun D. H. , Jeong J. , Kim Y.‐S.
Published: June 2007

A novel ultra‐wideband (UWB) bandpass filter in the whole UWB passband of 3.1–10.6 GHz is proposed and implemented using a uniplanar compact photonic bandgap (UC‐PBG) resonator for size reduction. Since the UC‐PBG structure has more distributed L‐C components than the conventional microstip multiple‐mode resonator (MMR), the size reduction is achieved, which is about 34% more than the UWB bandpass filter based on a conventional microstrip MMR. The proposed one‐stage UC‐PBG filter has four transmission poles, insertion loss < 1.2 dB and group delay variation < 0.14 ns, while the three‐stage one shows an insertion loss of < 2.2 dB and a group delay variation of < 0.4 ns in the whole UWB band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2122–2123, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22695
Rapid prototyping of ceramic millimeterwave metamaterials: Simulations and experiments
Authors: Lee Yoonjae , Lu Xuesong , Hao Yang , Yang Shoufeng , Ubic Rich , Evans Julian R. G. , Parini Clive G.
Published: June 2007

Rapid prototyping by an extrusion freeforming technique, of ceramic metamaterials based on a woodpile structure at millimeterwave frequencies has been performed. The finite difference time domain technique is applied for the design and characterization of the proposed metamaterials. The transmittance of the millimeterwave metamaterials is measured in the range of 75–110 GHz. Both measurement and simulation results are in good agreement. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2090–2093, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22697