bluuebunny/crossref_metadata_2025 huggingface dataset:
Transcriptional regulation of pyruvate kinase and phosphoenolpyruvate carboxykinase in the adductor muscle of the oyster Crassostrea gigas during prolonged hypoxia
Authors: Le Moullac Gilles , Bacca Hélène , Huvet Arnaud , Moal Jeanne , Pouvreau Stéphane , Van Wormhoudt Alain
Published: June 2007

The response of Crassostrea gigas to prolonged hypoxia was investigated for the first time by analyzing the metabolic branch point formed by pyruvate kinase (PK) and hosphoenolpyruvate carboxykinase (PEPCK). PK and PEPCK cDNAs were cloned and sequenced. The main functional domains of the PK sequence, such as the binding sites for ADP/ATP and phosphoenolpyruvate (PEP), were identified whereas the PEPCK sequence showed the specific domain to bind PEP in addition to the kinase‐1 and kinase‐2 motifs to bind guanosine triphosphate (GTP) and Mg2+, specific for all PEPCKs. A C‐terminal extension was detected for the first time in eukaryota PK. Separation of mitochondrial and cytosolic fraction showed that more than 92% of the PEPCK enzyme activity was cytosolic in gills, digestive gland, mantle and muscle. PK and PEPCK mRNAs and enzyme activities have been measured in muscle during prolonged hypoxia for 20 days. Adaptation of PK in hypoxic muscle at transcriptional level occurred lately by decreasing significantly the PK mRNA level at day 20 while PK enzyme activity was inhibited by the high content of alanine. The PEPCK mRNA ratio in hypoxic muscle significantly increased at day 10 simultaneously to the PEPCK enzyme activity. Succinate accumulation observed at day 10 and day 20 confirmed the anaerobic pathway of muscle metabolism in oyster subjected to hypoxia. Regulation of C. gigas PEPCK in muscle occurred at gene transcription level while PK was first regulated at enzyme level with alanine as allosteric inhibitor, and then at molecular level under a fast effect of hypoxia. J. Exp. Zool. 307A:371–382, 2007. © 2007 Wiley‐Liss, Inc.
Are babies better in autumn or spring? The consequences of extending gestation in a biennially reproducing viviparous lizard
Authors: Atkins Natalia , Swain Roy , Jones Susan M.
Published: June 2007

Niveoscincus microlepidotus, the southern snow skink, is a biennially reproducing alpine viviparous lizard with an extremely protracted gestation period: embryos are fully developed in autumn, but held over winter so that offspring are born in spring. The obvious benefits for offspring survival of delaying birth until spring have been demonstrated previously. To examine the consequences of deferred parturition for offspring characteristics, we compared neonates obtained in autumn by dissection with neonates born naturally in the spring. Our results demonstrate that deferral of parturition until spring represents a trade‐off between key offspring characteristics (spring neonates exhibit lower growth rates, reduced sprint speed after birth, reduced condition and decreased energy reserves) and offspring size [spring neonates are heavier (wet mass) and longer (snout‐vent length)]. Furthermore, when females are placed into cold experimental conditions in spring around the time of natural parturition, this species is able to defer parturition for an additional 4 weeks with no significant effect on offspring characteristics. Our results provide further evidence that flexibility in birth date provides a significant advantage to viviparous lizards living in cold climates. J. Exp. Zool. 307A:397–405, 2007. © 2007 Wiley‐Liss, Inc.
A stereophotographic study of ankle joint contact area
Authors: Millington Stephen , Grabner Markus , Wozelka Ralph , Hurwitz Shepard , Crandall Jeff
Published: June 2007

The purpose of this study was to measure the ankle joint contact area under physiological load magnitudes using a stereophotography technique that allows accurate analysis of the entire joint surface without disrupting the joint during loading. Ten cadaveric foot and ankle specimens were loaded to 1000 N in neutral, and 20° dorsiflexion, supination, pronation, and plantarflexion. Photo targets rigidly fixed to each of the bones were imaged in the loaded joint position using a high‐resolution stereophotography system. After testing, each ankle was disarticulated and the joint surfaces imaged relative to the photo targets. The photo targets were then used to spatially register the joint surfaces into the loaded joint position; the overlap of the surfaces was used to determine the joint contact area. The mean talo–tibia contact area was greatest in dorsiflexion 7.34 ± 1.69 cm2 and was significantly larger than in plantar flexion (p < 0.05), which showed the smallest joint contact area 4.39 ± 1.41 cm2. Considering talo–fibula, the maximum contact area was measured in dorsiflexion, 2.02 ± 0.78 cm2, and the minimum contact area occurred in pronation, 0.77 ± 0.49 cm2, respectively (p < 0.05). The reported stereophotography technique allows measurement of the joint contact area without disrupting the joint during loading. The contact area is larger than previously reported, as the entire joint surface was analyzed. Joint contact extends over both the talar dome and the talar shoulders where osteochondritis dissecans lesions commonly occur. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1465–1473, 2007
Microtopography of metal surfaces influence fibroblast growth by modifying cell shape, cytoskeleton, and adhesion
Authors: Meredith David O. , Eschbach Lukas , Riehle Mathis O. , Curtis Adam S. G. , Richards Robert G.
Published: June 2007

Stainless Steel (SS), titanium (cpTi), and Ti‐6Al‐7Nb (TAN) are frequently used metals in fracture fixation, which contact not only bone, but also soft tissue. In previous soft tissue cytocompatibility studies, TAN was demonstrated to inhibit cell growth in its “standard” micro‐roughened state. To elucidate a possible mechanism for this inhibition, cell area, shape, adhesion, and cytoskeletal integrity was studied. Only minor changes in spreading were observed for cells on electropolished SS, cpTi, and TAN. Cells on “standard” cpTi were similarly spread in comparison with electropolished cpTi and TAN, although the topography influenced the cell periphery and also resulted in lower numbers and shorter length of focal adhesions. On “standard” microrough TAN, cell spreading was significantly lower than all other surfaces, and cell morphology differed by being more elongated. In addition, focal adhesion numbers and mean length were significantly lower on standard TAN than on all other surfaces, with 80% of the measured adhesions below a 2‐µm threshold. Focal adhesion site location and maturation and microtubule integrity were compromised by the presence of protruding β‐phase microspikes found solely on the surface of standard TAN. This led us to propose that the impairment of focal adhesion numbers, maturation (length), and cell spreading to a possibly sufficient threshold observed on standard TAN blocks cell cycle progress and eventually cell growth on the surface. We believe, as demonstrated with standard cpTi and TAN, that a difference in surface morphology is influential for controlling cell behavior on implant surfaces. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1523–1533, 2007
Getting it done: Four ways to translate strategy into results
Authors: Yukl Gary , Lepsinger Richard
Published: June 2007

A recent survey indicates that many of today's business leaders believe their organizations are not only inadequate at implementing strategy but also unlikely to get better at this critical challenge. Other research on managers has identified four leadership behaviors that are useful in enhancing the execution of business strategy.
Functional Star‐Like Polystyrenes as Organic Supports of MeDIP(2,6‐iPrPh)2FeCl2 Catalyst Toward Ethylene Polymerization
Authors: Bouilhac Cécile , Cloutet Eric , Deffieux Alain , Taton Daniel , Cramail Henri
Published: June 2007

Star‐like polystyrenes composed of a microgel core with functionalized arms have been designed and used as organic supports for a tridentate bis(imino)pyridinyl iron catalyst toward ethylene polymerization. In a first approach, star‐like polystyrenes bearing a few number of ethylene oxide units at the periphery of each arm have been prepared to immobilize, through nucleophilic interactions, common aluminum‐based activators [methylaluminoxane or trimethylaluminum (TMA)]. A second strategy is based on the synthesis of star‐like PS with arms ended either by a benzophenone or a benzoic acid function. Indeed, the reaction of TMA with these functional microgels leads to the in situ formation of alkoxide aluminum‐based species at the periphery of the star‐like microgels. All these functional PS microgels have been used as supports to immobilize and activate the MeDIP(2,6‐iPrPh)2FeCl2 catalyst toward ethylene polymerization. High catalytic activities and polyethylene beads of spherical morphology, constituted of polyethylene chains of monomodal molar mass distribution have been obtained, thanks to the organic support.

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A Feasible Synthetic Route for Linear PTHF‐Hyperbranched Poly(phenyl sulfide) Block Copolymers
Authors: Zhu Zhichen , Pan Caiyuan
Published: June 2007

The linear‐hyperbranched block copolymers, in which the linear polytetrahydrofuran (PTHF) is linked to the apex of hyperbranched poly(phenylene sulfide) (HPPS‐SH), have been synthesized, and the synthesis includes condensation polymerization of 2,4‐dichlorobenzenethiol, subsequent transformation of the resultant HPPS‐SH to HPPS‐OH, and then the cationic ring‐opening polymerization of tetrahydrofuran (THF) using HPPS‐OH as a macrotransfer agent and BF3 · OEt2 as a catalyst. The resultant HPPSs have excellent thermal stability, the PTHF and HPPS chains were decomposed at 361 and 402 °C, respectively. HPPS can be dissolved in THF in the form of aggregates with Rh = 90 nm, which is larger than that (Rh = 55 nm) formed from the corresponding linear PTHF‐HPPS block copolymer.

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Effect of Polymer Architecture of Amphiphilic Poly(2‐oxazoline) Copolymers on the Aggregation and Aggregate Structure
Authors: Bonné Tune B. , Lüdtke Karin , Jordan Rainer , Papadakis Christine M.
Published: June 2007

The micelle formation of five poly(2‐oxazoline) diblock, triblock and gradient copolymers in water was investigated using fluorescence correlation spectroscopy. The polymers were synthesized by consecutive or simultaneous living cationic polymerization of 2‐methyl‐2‐oxazoline for the hydrophilic and 2‐nonyl‐2‐oxazoline for the hydrophobic polymer segments. Fractions of the polymers were fluorescence‐labeled at the polymer termini with TRITC for the FCS measurements. The hydrodynamic radii of solubilized polymer unimers and of the aggregates (micelles) were determined in a concentration range of 10−8–10−3 M and were found to depend in a characteristic way on the polymer architecture.

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Macromol. Chem. Phys. 12/2007
Authors: Papageorgiou George Z. , Achilias Dimitris S. , Bikiaris Dimitris N.
Published: June 2007

Cover: Non‐isothermal crystallization kinetics of poly(butylene succinate) can be described using either macroscopic models (such as the modified Avrami equation) or the effective activation energy calculated from isoconverional analysis. Lauritzen‐Hoffman parameters are estimated using a number of different techniques either from PLM or DSC data. Further details can be found in the Full Paper by G. Z. Papageorgiou, D. S. Achilias,* and D. N. Bikiaris on page 1250.
“Never eat in that restaurant, I did!”: Exploring why people engage in negative word‐of‐mouth communication
Authors: Wetzer Inge M. , Zeelenberg Marcel , Pieters Rik
Published: June 2007

What do consumers want to achieve when they engage in negative word‐of‐mouth communication (N‐WOM)? Two studies explore this question and reveal that consumers pursue specific goals when engaging in N‐WOM and that these goals systematically differ between the specific negative emotions that are experienced. For example, the results reveal that consumers who experience anger engage in N‐WOM to vent feelings or to take revenge. However, disappointed consumers engage in N‐WOM to warn others, and consumers who experience regret communicate with others to strengthen social bonds or to warn them. This reveals the functionality of specific emotions to N‐WOM, and how goals for N‐WOM are associated with these emotions. This demonstrates that rather than being uniform, the content and implications of N‐WOM are contingent on the specific emotions that consumers experience. © 2007 Wiley Periodicals, Inc.
L,L‐Lactide and ε‐Caprolactone Block Copolymers by a ‘Poly(L,L‐lactide) Block First’ Route
Authors: Florczak Marcin , Libiszowski Jan , Mosnacek Jaroslav , Duda Andrzej , Penczek Stanislaw
Published: June 2007

L,L‐lactide (LA) and ε‐caprolactone (CL) block copolymers have been prepared by initiating the poly(ε‐caprolactone) (PCL) block growth with living poly(L,L‐lactide) (PLA*). In the previous attempts to prepare block copolymers this way only random copolyesters were obtained because the PLA* + CL cross‐propagation rate was lower than that of the PLA–CL* + PLA transesterification. The present paper shows that application of Al‐alkoxide active centers that bear bulky diphenolate ligands results in efficient suppression of the transesterification. Thus, the corresponding well‐defined di‐ and triblock copolymers could be prepared.

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Morphology Transition in Ultrathin Titania Films: From Pores to Lamellae
Authors: Cheng Ya‐Jun , Zhou Shaoying , Gutmann Jochen S.
Published: June 2007

Nanostructured TiO2 thin films were prepared using an amphiphilic PS‐b‐PEO block copolymer as a templating agent. A good–poor solvent pair‐induced pair phase separation process was coupled with sol–gel chemistry to control the morphology of the TiO2 film in a solution of 1,4‐dioxane, concentrated HCl, and titanium tetraisopropoxide (TTIP). By varying the block copolymer concentration from 0.25 to 4.0 wt.‐% while keeping the relative ratios among 1,4‐dioxane, conc. HCl, and TTIP constant, a morphology transition from pores to lamellae was observed. The photoluminescence (PL) properties of the film composed of different morphologies were studied, and the PL properties were found to be independent of the morphologies of the mesoporous films. The mechanism of the morphology evolution with respect to the copolymer concentration is further discussed.

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NMR Reveals Non‐Distributed and Uniform Character of Network Chain Dynamics
Authors: Saalwächter Kay , Sommer Jens‐Uwe
Published: June 2007

Results of different NMR investigations of elastomers are reviewed with respect to their significance for statistical models of rubber elasticity. In contrast to earlier work based on lineshape analysis and relaxometry, results of recent multiple‐quantum experiments indicate that the NMR‐detected dynamic chain order parameter, which reflects the conformational space of individual monomer units at which the signal is detected locally, is a rather narrowly distributed quantity. Constraints to the dynamics and the conformations of a network chain thus act uniformly and appear as a dynamic average over chains of different length and with different end‐to‐end separations. All our findings are in good agreement with large‐scale computer simulations. Anomalies on swelling such as chain desinterspersion at the early stages and the appearance of heterogeneities, are also discussed.

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Towards Controlled Graft Polymerization of Poly[styrene‐co‐(maleic anhydride)] on Functionalized Silica Mediated by Oxoaminium Bromide Salt. Facile Synthetic Pathway Using Nitroxide Chemistry
Authors: Bonilla‐Cruz José , Lara‐Ceniceros Tania , Saldívar‐Guerra Enrique , Jiménez‐Regalado Enrique
Published: June 2007

A TEMPO bromide salt is used to functionalize a silica surface with nitroxyl moieties. The functionalization reaction takes place in 48 h under mild conditions. In a second step, grafts of styrene‐maleic anhydride copolymer are grown from the functionalized silica surface by heating it in the presence of the monomers. FT‐IR and TGA analysis show that the silica was first functionalized with nitroxide moieties, and then that grafts of styrene‐maleic anhydride grew from the functionalized silica surface. A reaction mechanism is proposed in order to explain the findings. The results suggest that the oxoaminium salts are good candidates for the functionalization and grafting of surfaces that contain hydroxy groups and for the generation of hybrid materials with improved properties.

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A Preparation Method for Well‐Defined Crystallites of Mgcl2‐Supported Ziegler‐Natta Catalysts and their Observation by AFM and SEM
Authors: Andoni Adelaida , Chadwick John C. , Niemantsverdriet Hans J. W. , Thüne Peter C.
Published: June 2007

A method for the preparation of well‐defined crystallites of MgCl2‐supported Ziegler‐Natta catalysts on Si wafers has been developed. This has been achieved by the spin‐coating of a MgCl2 solution onto a flat Si wafer, followed by controlled crystal growth to give well‐defined MgCl2 · nEtOH crystallites. The growth of the crystallites on the flat silica facilitates their characterization using electron and scanning probe microscopy. The relative proportions of 120° and 90° edge angles indicate the preference for the formation of a particular crystallite face for the MgCl2. Polyethylene has been identified to be formed on the lateral faces of the crystallite.

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Neue Kapseltechnik für Diamantverbundwerkstoffe mittels PVD‐Verfahren
Authors: Tillmann W. , Gathen M. , Vogli E. , Ullrich C.
Published: June 2007

Für die Bearbeitung mineralischer Materialien werden Diamantwerkzeuge bestehend aus diamantimprägnierten Segmenten, aufgelötet auf Stahlträgerkörpern eingesetzt. Diese Segmente werden häufig mittels Heißpressen hergestellt. Weitere Herstellungsverfahren sind druckloses Sintern von Grünkörpern teilweise kombiniert mit heißisostatischem Pressen und das heißisostatische Pressen gekapselter Pulvermischungen. Der Verdichtungseffekt des heißisostatischen Pressprozesses erfordert eine geringe Porosität der Sinterkörper erzielt durch die Verwendung ultra‐feiner Metallpulver oder den Einsatz gasdichter Metall‐ oder Glaskapseln. Der Lehrstuhl für Werkstofftechnologie verfolgt eine neuartige Herstellungsroute, bei der mittels PVD‐Verfahren eine Beschichtung auf den drucklos gesinterten Sinterkörpern abgeschieden wird. Diese dünne Schicht wirkt ähnlich einer Kapsel und garantiert die Druckübertragung während des anschließenden heißisostatischen Pressprozesses. Trotz des Einsatzes von Bronzepulvern mit Korngrößen bis zu 90 μm ist die Herstellung dichter diamantimprägnierter Verbundwerkstoffe möglich. Im Vergleich zu konventionellen Kapseltechniken liegt der Vorteil dieser neuen Prozessroute in dem Einsatz verhältnismäßig grober Metallpulver und der hohen geometrischen Flexibilität.
First case of X‐linked dystonia‐parkinsonism (“Lubag”) to demonstrate a response to bilateral pallidal stimulation
Authors: Evidente Virgilio Gerald H. , Lyons Mark K. , Wheeler Mark , Hillman Renee , Helepolelei Luann , Beynen Froukje , Nolte Dagmar , Müller Ulrich , Starr Philip A.
Published: June 2007

“Lubag” or X‐linked dystonia‐parkinsonism (XDP) is a genetic syndrome afflicting Filipino men. Intracranial surgical procedures for Lubag have been unsuccessful. We report a 45‐year‐old Filipino male with genetically confirmed XDP who underwent bilateral pallidal deep brain stimulation (DBS) surgery. The patient started to exhibit improvement on initial programming, most notably of his severe jaw‐opening dystonia. At 1‐year follow‐up, his Burke‐Fahn‐Marsden dystonia score and motor Unified Parkinson's Disease Rating Scale score were improved by 71% and 62%, respectively, with the stimulators on compared to stimulators off state. Bilateral pallidal DBS may be a viable option for Lubag patients with medically refractory symptoms. © 2007 Movement Disorder Society
Variation of selective gray and white matter atrophy in Huntington's disease
Authors: Jech Robert , Klempíř Jiří , Vymazal Josef , Židovská Jana , Klempířová Olga , Růžička Evžen , Roth Jan
Published: June 2007

The relationship between the extent of local gray/white matter atrophy, genetic load, and clinical impairment was studied in Huntington's disease (HD) by means of voxel‐based morphometry. T1‐weighted brain images from 33 patients (mean age 49.5, range 25–73 years) with HD duration of 1 to 15 years were analyzed by correlation of each voxel intensity with the number of CAG triplets and the UHDRS‐motor score (P < 0.001). The CAG number correlated inversely with gray matter intensity in the caudate nuclei and with white matter intensity in the both postcentral gyri and the right cerebellum. The UHDRS‐motor score correlated inversely with the atrophy of both caudates, right hippocampus, calcarine fissure, and with the white matter along the fourth and lateral ventricles. While atrophy of the caudate nucleus was related to a higher number of CAG triplets and higher UHDRS‐motor score, atrophy in other parts of the brain covaried with the two parameters differently: higher genetic load was associated with greater loss of cortical somatosensory projections and the worse UHDRS‐motor score was accompanied by increased atrophy of the internal capsule, lower brainstem, hippocampus, and visual cortex. According to our results, the genetic load in HD predicts partially the extent of selective gray/white brain matter atrophy, which is then reflected in the severity of motor impairment. © 2007 Movement Disorder Society
Dopa‐responsive pseudo‐orthostatic tremor in parkinsonism
Authors: Thomas Astrid , Bonanni Laura , Antonini Angelo , Barone Paolo , Onofrj Marco
Published: June 2007

In four patients an inabilitating standing tremor appeared years before that parkinsonian symptoms were evidenced. This tremor was refractory to gabapentin and dramatically responded to Levodopa administration. Its dominant frequency was 6.2 to 6.9 Hz with sporadic subharmonics at 8 to 18 Hz. Three patients were affected by different genetic mutations (Park 2, Park 6, mtDNA deletion) in one no genetic or metabolic alterations could be evidenced. All patients had dopamine transporter abnormalities. We suggest that the term “Pseudo‐Orthostatic Tremor” could be used to define this Dopa responsive, 6 to 7 Hz standing tremor. © 2007 Movement Disorder Society
Navier–Stokes equations in aperture domains: Global existence with bounded flux and time‐periodic solutions
Authors: Crispo Francesca , Maremonti Paolo
Published: June 2007

We consider the Navier–Stokes equations in an aperture domain of the three‐dimensional Euclidean space. We are interested in proving the existence of regular solutions corresponding to small initial data and flux through the aperture. The flux is assumed to be smooth and bounded on (0, +∞). As a consequence, we prove the existence of a time‐periodic solution corresponding to a time‐periodic flux through the aperture. Finally, we compare our solution with a solution belonging to a wider class, showing that, if such a solution does exist, then the two solutions coincide. Copyright © 2007 John Wiley & Sons, Ltd.
Role of dietary lignans in the reduction of breast cancer risk
Authors: Saarinen Niina M. , Wärri Anni , Airio Maarit , Smeds Annika , Mäkelä Sari
Published: June 2007

Lignans are a large group of fiber‐associated phenolic compounds widely distributed in edible plants. Some of the ingested plant lignans are converted by intestinal microbiota to enterolignans, enterodiol (END) and enterolactone (ENL), the latter of which has been thought to be the major biologically active lignan, and suggested to be associated with low risk of breast cancer. In line with this, administration of plant lignans which are further metabolized to ENL, or ENL as such, have been shown to inhibit or delay the growth of experimental mammary cancer. The mechanism of anticarcinogenic action of ENL is not yet fully understood, but there is intriguing evidence for ENL as a modulator of estrogen signaling. These findings have generated interest in the use of lignans as components of breast cancer risk reducing functional foods. Identification of target groups, who would benefit most, is of pivotal importance. Therefore, further identification and validation of relevant biomarkers, which can be used as indicators of lignan or ENL action and breast cancer risk reduction at different stages of the disease, are of importance.
Bioavailability of soy isoflavones in rats Part I: Application of accurate methodology for studying the effects of gender and source of isoflavones
Authors: Sepehr Estatira , Cooke Gerard , Robertson Patrick , Gilani G. Sarwar
Published: June 2007

There are limited and controversial reports about the effects of gender and source of isoflavones on their bioavailability. Moreover, several previous studies have not used appropriate methodology to determine the bioavailability of soy isoflavones, which requires comparing the area under the plasma concentration‐time curve after both oral and intravenous injection (IV) administration. Therefore, the present study was conducted to determine the bioavailability of isoflavones from different sources following both oral and IV administration in male and female rats. Three sources of isoflavones; NovasoyTM (a commercial supplement), a mixture of synthetic aglycones (daidzein, genistein and glycitein) and a mixture of synthetic glucosides (daidzin, genistin and glycitin) were tested. Following administration, blood samples were collected at several time points (0, 10, 30 min and 1, 2, 8, 24, 48 h post oral gavage and 0, 10, 30, 45 min and 1, 2, 3, 4, 8 h post‐IV dosing) and plasma isoflavones were measured by LC/MS. Bioavailability values for daidzein, genistein and glycitein were significantly (p <0.05) higher (up to sevenfold) in NovasoyTM and the glucoside forms of isoflavones compared with those of the aglycone forms. Moreover, significant (p <0.05) gender differences in the bioavailability of 7‐hydroxyl‐3‐(4′‐hydroxyphenyl)‐chroman (a metabolite of daidzein), glycitein and daidzein were observed for NovasoyTM, with higher values in male rats. In summary, the source of isoflavones and the sex of rats had significant effects on isoflavone bioavailability.
Simplified description of asymmetric right‐handed composite right/left‐handed coupler in microstrip chip technology
Authors: Wang Youzhen , Zhang Yewen , Liu Fuqiang , He Li , Li Hongqiang , Chen Hong , Caloz Christophe
Published: June 2007

The coupling frequency range of the asymmetric coupler composed of a conventional microstrip right‐handed (RH) transmission line and a composite right/left‐handed (CRLH) transmission line with lumped‐elements is investigated. It shows theoretically that the coupling frequency range can be explicitly determined by the given formulas. In the coupling frequency range, the effective permittivity and permeability of the CRLH transmission lines are both negative, at the same time the product of the average permittivity and the average permeability is negative, i.e., ϵL < 0, μL < 0, and $\bar{\varepsilon}$ · $\bar{\mu}$ < 0. Two types of RH‐CRLH couplers are designed, simulated, and measured. The coupling frequency range obtained from the simulated and the experimental results confirms the theoretical results. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2063–2068, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22643
Compact printed semi‐elliptical monopole antenna for super‐wideband applications
Authors: Yan Xiao‐Rong , Zhong Shun‐Shi , Liang Xian‐Ling
Published: June 2007

A compact semi‐elliptical patch antenna fed by a tapered coplanar waveguide is introduced for super‐wideband (SWB) applications. The simulated and experimental results demonstrate that the antenna possesses the desirable SWB characteristics, achieving a ratio bandwidth of 19.7:1 for VSWR ≤ 2, and exhibits a nearly omni‐directional radiation pattern, while its area is only about 0.15λl × 0.21λl, where λl is the wavelength of the lowest operating frequency. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2061–2063, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22644
A bandpass filter with harmonic suppression using SIR and zigzag coupling
Authors: Guan Fu‐Hong , Gu Jian‐Zhong , Sun Xiao‐Wei
Published: June 2007

This article presents a new compact, low‐insertion loss, wide stopband, and narrow‐band microstrip bandpass filter using a step‐impedance resonators. A compact filter operated at 2.13 GHz is designed. Experimental results show that the insertion loss of the filter is 1.08 dB and the upper stopband is extended over 8.5 GHz. The effect of varying the width and shape of the couple line to the performance of the filter has been studied. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2071–2074, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22647
Spiral patch with wideband and circular polarization for millimeter‐wave communication
Authors: He Wei , Jin Ronghong , Yang Junping G. G.
Published: June 2007

In this study, a spiral patch antenna operating millimeter‐wave band is proposed. Using this spiral structure, the patch antenna is designed for circular polarization and wideband operation at about 30.8–36.9 GHz for millimeter‐wave communication. Simulated and measured results for main parameters such as return loss, impedance bandwidth, radiation patterns, and gains are also discussed herein. The study shows that the modeling of such antennas, with simplicity in designing and feeding, can well meet millimeter‐wave wireless communication. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2068–2071, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22648
Simultaneous noise and input matched ultra wide band LNA design
Authors: Shim Yuna , Kim Chang‐Wan , Lee Sang‐Gug
Published: June 2007

Proposed a low noise amplifier (LNA) design technique that satisfies simultaneous noise and input matched condition over ultra wide band (UWB) frequency range. Simultaneously, noise‐ and input‐matched UWB LNA is implemented in 0.18 μm CMOS technology, and measurements show higher than 8 dB of input return loss, maximum gain of 10.5 dB, and noise figure of 3.9–6 dB over 2–4 GHz while dissipating 4 mA from a 1.8‐V supply. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2275–2279, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22650
Effects of varying the series capacitance in CSRR‐loaded metamaterial transmission lines
Authors: Vélez Adolfo , Bonache Jordi , Martín Ferran
Published: June 2007

In this work, the effects of varying the series capacitance in metamaterial transmission lines consisting on a microstrip line loaded with complementary split rings resonators (CSRRs) and series capacitors are analyzed in detail. It is found that by varying the series capacitance, the transmission characteristics of the line can be tailored. Specifically, the typical transmission zero present below the left handed band, as well as the limits of this band, are modified. It is even possible to balance the line by properly tuning the structure. These results are interpreted to the light of the equivalent circuit model of the unit cell. Comparison between experiment and theory supports the interpretation of the results. This work opens the door to the design of reconfigurable microwave components based on complementary split rings resonator‐loaded lines. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2245–2248, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22651
Broad band behavioral modeling of on‐chip RF inductors and transformers
Authors: Bhattacharya Rajarshi , Bhattacharyya T. K. , Dutta Asudeb
Published: June 2007

The broad band behavioral models of on‐chip inductors and transformers are extracted from sampled frequency response data. A linearized least square based model parameter extraction algorithm is used to obtain ‘s’‐domain rational function model. Model order is optimized to strike a balance between modeling error and time required for transient simulation of circuits consisting of on‐chip inductors and/or transformers. A new cost function is proposed to improve optimal model order selection. Particle swarm optimization (PSO) is applied to maximize the nonconvex fitness function, associated with model order optimization. A modification of PSO algorithm is proposed to speed up optimal model order selection. While modeling on‐chip inductors and transformers, the proposed modeling technique extracts highly accurate, yet reduced order models, which are valid over a wide band width and are compatible with SPICE‐like simulators. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2212–2216, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22653
Design of Yagi‐like printed antennas for WLAN applications
Authors: Ávila‐Navarro E. , Carrasco J. A. , Reig C.
Published: June 2007

A directive broadband printed Yagi‐like antenna design is presented. We have focused on the 2.45 GHz WLAN band, at which some designs have been carried out. For the design and the modelling processes, we made use of FDTD based in‐house developed algorithms. Some selected prototypes have then been fabricated onto a low‐cost printed circuit board dielectric substrate and tested successfully. Bandwidths higher than 10% and moderate to high (>7 dBi) gains can be obtained this way. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2174–2178, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22655
A half‐moon antenna with tilt angles for wideband applications
Authors: Jung Chang Won , Kim Yongjin
Published: June 2007

A half‐moon antenna is presented for wideband communication system. The proposed antenna radiates linear polarized wave omnidirectionally in wide frequency band from 1.5 GHz to more than 5 GHz (>∼110%). The frequency bands of the proposed antenna are investigated from the variable current path lengths by tilting angles. The overall radiation gain of the proposed antenna is 2–3 dBi. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2171–2174, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22656
High frequency RFID smart table antenna
Authors: Cai Ailian , Qing Xian Ming , Chen Zhi Ning
Published: June 2007

In this paper, loop antenna is investigated for high frequency (HF) radio frequency identification (RFID) smart table application. The antenna is optimized by making a compromise between the coverage and detection range. The performance test shows that the antenna is capable of detecting 90 plastic plates in a specific area (500 × 500 mm2) and achieving a detection rate of 100% when it was installed below a wood/plastic table. The proposed antenna has been successfully implemented in an HF RFID smart table prototype for a restaurant to count food plates and bill customers automatically. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2074–2076, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22662
Determining transmission zeroes of the general Chebyshev filter
Authors: Chu Qing‐Xin , Tu Zhi‐Hong
Published: June 2007

Determining transmission zeroes is the important precondition in the synthesis of the cross‐coupled filter. A novel method to determine the general Chebyshev filter degree and transmission zeroes at the same time is proposed, according to the extreme characteristic of the general Chebyshev function and the relationship between the filter degree and the number of transmission zeros. On the condition of given filter specifications, the least filter degree and the optimum positions of transmission zeroes are realized. Several application examples illustrate the procedure and the validity of the proposed method. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2270–2275, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22663
Retrofittable antireflection coatings for T‐rays
Authors: Withayachumnankul Withawat , Fischer Bernd M. , Mickan Samuel P. , Abbott Derek
Published: June 2007

T‐ray reflection loss at a window's surface is reduced by means of a quarter‐wave antireflection coating. Because T‐ray wavelengths are much longer than visible wavelengths, the antireflection layer for T‐rays is much larger than the layers typically used in optics. This creates an interesting opportunity for retrofittable antireflection layers. In the experiment, an antireflection coating made from ordinary polyethylene sheets is pressed onto the surfaces of a silicon window in the way that rapid replacement of the rettrofittable coating is possible. Measured by terahertz time‐domain spectroscopy (THz‐TDS), the coated window shows enhancement of the transmittance within a range of T‐ray frequencies. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2267–2270, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22664
Design of dual‐band filter using defected split‐ring resonator combined with interdigital capacitor
Authors: Wu B. , Fan J. W. , Zhao L. P. , Liang C. H.
Published: June 2007

A novel type of dual‐band microstrip structure and its equivalent circuit are investigated, which is composed of defected split‐ring resonator and interdigital capacitor. The influence of design parameters on the frequency characteristics is discussed, then a dual‐band microstrip filter, which has two passbands of 1.8–2.5 GHz and 5.5–5.9 GHz with a transmission zero, is designed and fabricated. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2104–2106, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22673
Design of ultra wideband 3DB quadrature microstrip/slot coupler
Authors: Abbosh A. M. , Bialkowski M. E.
Published: June 2007

This article presents the configuration and design method of a compact ultra wideband 3dB quadrature coupler employing a microstrip/slot technology. The proposed device uses two substrates with a common ground plane. It is formed by two identical multisection elliptical conducting strips, which are broadside coupled through a multisection elliptical slot in the ground plane. Results of simulation and measurements show that the coupler exhibits a coupling equal to 3 ± 1 dB for the band 2.3–12.3 GHz. The isolation and return loss are better than 23 dB across that band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2101–2103, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22674
Continuous measurements of granular materials permittivities in microwave range
Authors: Li Yue‐e , Ding Guangze , Xu Fuyong
Published: June 2007

Most of numerous available measurement techniques of microwave dielectric property are static measurement, and their specimen preparations are complex and tedious. In this article, a novel trapezoidal groove guide sensor for achieving continuous measurement is designed, and has been applied in measuring the moisture of the granular materials. Rigid theoretical formulas have been educed. The measured experimental cures are in good agreement with the theoretical curves. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2234–2236, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22677
A new phenomenon in GaAs photoconductive semiconductor switches triggered by laser diode
Authors: Sun Yanling , Shi Shunxiang , Zhu Yanwu , Wu Xin
Published: June 2007

A new phenomenon in GaAs photoconductive semiconductor switches triggered by laser diodes is reported. It occurs when the switch is biased under the threshold and triggered by serial laser pulses. This phenomenon reflects the carrier accumulation effect when the switch operates at the nonlinear mode. The effects of bias voltage and optical pulse energy on the carrier accumulation are investigated. The results indicate that number of carrier can be controlled by adjusting bias voltage and optical pulse energy. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2232–2234, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22678
CAD formulas for patch dimensions of rectangular microstrip antennas with various substrate thicknesses
Authors: Akdagli Ali
Published: June 2007

This letter presents the closed‐from formulas for determining the patch dimensions of electrically thin and thick rectangular microstrip antennas. The presented formulas constructed by utilizing a differential evolution algorithm become very useful as computer‐aided design (CAD) models for patch antenna design. A comparison between the calculated and experimental results derived from 33 patch antennas demonstrates that the proposed CAD formulas provide <0.16% and 0.22% errors on average for the patch length and patch width, respectively. The results obtained by using the formulas given here are found to be closer to the experimental values, as compared with previous results presented by several researchers. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2197–2201, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22679
A high temperature superconducting group‐delay equalizer
Authors: Zuo Tao , Fang Lan , Yan Shaolin , Zhao Xinjie , Zhou Tiege , Ji Lu , Zhang Xu , Xie Qinglian , Wu Zhizhen
Published: June 2007

A planar structure of group‐delay equalizer, which is built on high temperature superconducting (HTS) films, is proposed in this article. The HTS equalizer consists of one microstrip 3‐dB hybrid and two identical 1‐port coupled‐resonator filters. Compared with the traditional equalizers composed of cavity or coaxial resonators, the HTS equalizer has the advantages of smaller insertion loss and smaller size. As an example, a 3‐pole HTS equalizer is designed to equalize a 6‐pole HTS filter and good performance is achieved. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2163–2165, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22681
Dual and triple‐band PIFA design for WLAN applications
Authors: Sim Chow‐Yen‐Desmond
Published: June 2007

The design of a dual and triple‐band planar inverted‐F antenna (PIFA) is proposed for WLAN 802.11 a/b/g applications. Dual‐band operation is achieved by simply truncating one of the top rectangular radiating plate's corners, and wide bandwidth for the upper‐band is obtained by applying an additional small rectangular slit. By further extending the slit length, a triple‐band operation can also be achieved with a maximum gain of around 5 dBi. Simulated results are provided to validate the measured results. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2159–2162, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22682
Triangular slot antenna with a double‐T‐shaped tuning stub for wideband operation
Authors: Yoon JoongHan
Published: June 2007

In this study, a triangular slot antenna fed by a double‐T‐shaped tuning stub for wide bandwidth is proposed and experimentally studied. The prototype consists of a triangular slot model and double‐T‐shaped tuning stub. The effect of various parameters of the double‐T‐shaped tuning stub on wideband operation is investigated. From the experimental results, the measured impedance bandwidth, defied by VSWR 1:2, was found capable of reaching an operating bandwidth of 3.384 GHz, or 83.19%. The antenna radiation patterns and gains within the operating band were also measured and studied. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2123–2128, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22684
Geometrically based power azimuth spectrum models for mobile communication systems
Authors: Jiang Lei , Tan Soon Yim
Published: June 2007

A geometrically base single bounce power azimuth spectrum model for mobile communication systems is proposed in this article. The scatterers are assumed to distribute around the transmitting antenna within a circular region. The distribution of the scatterers can be arbitrary, e.g., Rayleigh, exponential etc. Power azimuth spectrums are derived for these propagation environments. Comparisons between our theoretical calculations and the empirical results as well as the measurement data reported in the literature show that the Rayleigh distribution scatterer models is applicable for the outdoor microcell propagation environment, while the exponential distribution scatterer model is accurate for the indoor office/laboratory propagation environment. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2093–2097, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22686
All‐fiber actively Q‐switched Er3+/Yb3+ co‐doped ring laser
Authors: Zhang Shu‐Min , Lu Fu‐Yun , Wang Jian
Published: June 2007

We report on a all‐fiber actively Q‐switched laser based on a Mach‐Zehnder interferometer (MZI). One of the arms of the MZI is bonded on a piezoelectric transducer (PZT). The path length difference between those two arms will change when a RF electric signal is applied drives the PZT, allowing control of the Q‐factor of the cavity and, thus, performing active Q‐switching. Using Er3+/Yb3+ co‐doped fiber (EYDF) and a maximum pump power of 712 mW, Q‐switch pulses with peak power of 2.2 W and pulse width of 1.2 μs were obtained. Furthermore, our result also shows that, to generate stable Q‐switched‐pulses, with different pump power, one must select different modulation frequency, this phenomenon is experimentally proved for the first time to our knowledge. The pulse repetition rate of the laser can be adjusted from few Hz up to 25 kHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2183–2186, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22692
Wide coverage area of UHF‐band RFID system using a pattern reconfigurable antenna
Authors: Rhyu Hanphil , Harackiewicz Frances J. , Lee Byungje
Published: June 2007

A new type of a reader antenna for a UHF‐band RFID system is proposed to cover a wider area. The proposed antenna consists of a circular polarized patch element, an omnidirectional electrical loop element, and a feeding network. By combining two antenna elements whose radiation patterns and half‐power beamwidths (HPBW) are different from each other, the coverage area of the RFID system is increased. The experimental results show the proposed antenna has a HPBW of more than 120° and works well in the UHF band RFID system. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2154–2157, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22694
Electromagnetically coupled microstrip square/circular ring resonators: Inset/offset feed variation effects on resonance frequency
Authors: Ghanbari Hossein , Karekar Ravi N. , Aiyer Rohini C.
Published: June 2007

Inset/offset feed‐dependent variation of electromagnetically coupled microstrip square and circular ring resonators (MSRR/MCRR) over a wide range indicate overall increase and decrease in resonant frequency (fr) respectively. On the basis of the experimental results, equations are suggested to determine fr as a function of the normalized inset and offset feed positions. Equations are validated for a limited range. High values of quality factor Q = 618 are obtained with MSRR as compared with MCRR (Q = 375) at two offset points near the ring edge with VSWR ≈ 1. This advantage can be used for applications such as frequency‐selective circuits and sensors. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2118–2121, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22696