bluuebunny/crossref_metadata_2025 huggingface dataset:
Selectivity differences between alkyl and polar‐modified alkyl phases in reversed phase high performance liquid chromatography
Authors: Jing Lin‐Lin , Jiang Ru , Liu Peng , Wang Ping‐An , Shi Tian‐Yao , Sun Xiao‐Li
Published: December 2008

Compared to conventional C18 phases, polar‐modified phases have distinct differences with regards to chromatographic behavior. In the present study, ODS phases and polar‐modified phases were synthesized. The columns containing these new packings demonstrated satisfactory stability under both acidic (pH 1.5) and basic (pH 10) conditions. We evaluated the selectivity differences between alkyl and polar‐modified alkyl RP columns by using a range of neutral analytes. The polar‐modified alkyl phases showed excellent peak shapes for almost all compounds. We also compared the selectivity differences between them for separating nucleotides by using 100% aqueous mobile phase and tricyclic antidepressants in the intermediate pH mobile phases. The results demonstrated that polar‐modified phases display a significantly reduced hydrophobic nature and a significantly reduced silanol activity compared to the conventional C18 phases.
Simultaneous determination of pyrethroids from pesticide residues in porcine muscle and pasteurized milk using GC
Authors: Khay Sathya , Abd El‐Aty A. M. , Choi Jeong‐Heui , Shin Eun‐Ho , Shin Ho‐Chul , Kim Jin‐Suk , Chang Byung‐Joon , Lee Chi‐Ho , Shin Sung‐Chul , Jeong Ji Yoon , Shim Jae‐Han
Published: December 2008

The principal goal of this work was to develop an efficient method for the simultaneous determination of four pyrethroid (PYR) insecticides, cyfluthrin, cyhalothrin, cypermethrin, and deltamethrin, in porcine muscle and pasteurized milk using liquid–liquid extraction (LLE). Sample extraction was carried out with and without additional column cleanup procedures, and the final determination was made using GC with electron‐capture detector (ECD). The pesticide identity was confirmed using GC‐MS in the SIM mode. Since there were minor differences between the extraction procedures, extraction without the additional cleanup procedure was used throughout the work. The method was validated by fortifying blank samples with half, two, and four times the maximum residue limit (MRL) of each PYR. The average recoveries (n = 6) ranged from 83.5 to 99.2% and 82.9 to 109% in porcine muscle and pasteurized milk, respectively. The repeatability of measurements expressed as RSDs, was in the range of 1.7–11.9 and 1.5–10.3% in porcine muscle and pasteurized milk, respectively. The LODs ranged from 3.3 to 9 and 3 to 8.1 ppm, whereas the LOQs ranged from 10 to 27.4 and 9 to 24.6 ppm, in porcine muscle and pasteurized milk, respectively. The applicability of the method was demonstrated by analyzing real samples collected from major cities in the Republic of Korea. No residues of the selected pesticides were detected in any of the samples.
Effects of early nightmares on the development of sleep disturbances in motor vehicle accident victims
Authors: Kobayashi Ihori , Sledjeski Eve M. , Spoonster Eileen , Fallon William F. , Delahanty Douglas L.
Published: December 2008

The present study prospectively examined the extent to which trauma‐related nightmares affected the subsequent development of insomnia symptoms in 314 motor vehicle accident (MVA) victims. Participants were assessed in‐hospital and at 2 weeks, 6 weeks, 3 months, and 1 year post‐MVA. Hierarchical linear regression analyses showed that 6‐week PTSD symptoms (PTSS) and 3‐month nightmares, but not 2‐week nightmares were positively associated with sleep onset and maintenance problems reported at 3‐month post‐MVA. Nightmares reported at 3‐months post‐MVA were positively associated with 1‐year sleep maintenance problems. These findings highlight the dynamic relationship between PTSS and sleep problems as well as the potential importance of early intervention for trauma‐related nightmares as a means to prevent sleep problems after a traumatic experience.
Low cortisol, high DHEA, and high levels of stimulated TNF‐α, and IL‐6 in women with PTSD
Authors: Gill Jessica , Vythilingam Meena , Page Gayle G.
Published: December 2008

Posttraumatic stress disorder (PTSD) has been associated with hypothalamic–pituitary–adrenal (HPA) axis and immune function alterations; however, few studies have simultaneously investigated these systems in participants with PTSD. In this study, HPA axis and immune function in 26 women with PTSD with and without major depressive disorder was compared to 24 traumatized controls and to 21 nontraumatized controls. Posttraumatic stress disorder was associated with low cortisol and higher levels of DHEA and greater production of tumor necrosis factor‐α (TNF‐α) and interleukin‐6 (IL‐6) compared to traumatized and healthy controls. Women with PTSD and depression exhibited greater production of IL‐6 and higher levels of dehydroepiandrosterone (DHEA) than those with PTSD, but without depression. These findings suggest dysregulated HPA axis and immune function in women with PTSD, and that comorbid depression may contribute to these abnormalities.
Early intervention for trauma: Where are we and where do we need to go? A commentary
Authors: Litz Brett T.
Published: December 2008

In this commentary, the author underscores the importance of early intervention for trauma and describes the challenges that lie ahead for researchers, decision makers, and care providers. The author also provides a review of where things stand, briefly reviews psychological first aid strategies, and underscores where we need to go from here. Although the field has advanced considerably in the last decade or so, and there are compelling trials underway, there is much work that needs to be done, especially in terms of effectiveness and the task of integrating early intervention into various work cultures, such as the military.
Using evidence to inform clinical practice shortly after traumatic events
Authors: Bisson Jonathan I.
Published: December 2008

Despite ongoing gaps in our knowledge, there is now considerable research evidence available to inform clinical decisions and treatment plans shortly after traumatic events. The author uses two fictional cases to illustrate an evidence‐based approach to clinical management following traumatic events. The importance of fully assessing individuals and tailoring management plans to address their specific needs optimally is highlighted by considering two distinct, but familiar types of presentation.
PTSD symptoms, forgiveness, and revenge among Israeli Palestinian and Jewish adolescents
Authors: Hamama‐Raz Yaira , Solomon Zahava , Cohen Assaf , Laufer Avital
Published: December 2008

Exposure to political terror and its psychological toll were assessed in 276 Israeli Palestinian and 1,469 Jewish adolescents using self‐report questionnaires. Israeli Palestinians displayed more posttraumatic symptoms, higher levels of objective exposure to terror, more negative life events, lower ability to forgive, and a higher need for vengeance than their Jewish counterparts. Although the two groups did not differ in fear levels, Israeli Palestinians expressed more favorable attitudes toward peace. Ethnicity played a major role in explaining the variance of posttraumatic symptomatology. Israeli Palestinians displayed increased vulnerability to mental distress when compared to their Jewish counterparts. The unique roles of subjective fear, attitudes towards peace, forgiveness, and revenge among Israeli Palestinians are discussed.
Impact of lignite washery sludge on mine soil quality and poplar trees growth
Authors: Dželetović Ž. S. , Filipović R. M. , Stojanović D. Dj. , Lazarević M. M.
Published: December 2008

This paper outlines research on the use of lignite washery sludge as the amendment for reclamation of lignite mine soil and stimulating poplar trees growth. Sludge is characterized by high total C content (∼34%) and high C/N ratio (68:1). The sludge was introduced by ploughing in, down to 20–25 cm depth, in the quantities: 0, 28, 56 and 112 t ha−1. We have established that the N percentage in poplar leaves decreases with introducing increasing quantities of sludge into the mine soil. On the other hand, the content of B and Cd increased with increasing sludge quantities. The As content in poplar leaves did not correlate with the applied quantities of sludge, but it did with the P, Fe and Zn content in the leaves. Introducing this sludge can have a positive effect on annual tree trunk increment, but only in the subsequent phases of growth. In the first few years an increase of total C content by introducing lignite washery sludge is not sufficient to provide the conditions for faster growth of trees. Copyright © 2008 John Wiley & Sons, Ltd.
Accumulation and composition of total organic carbon in reclaimed coal mine lands
Authors: Ganjegunte G. K. , Wick A. F. , Stahl P. D. , Vance G. F.
Published: December 2008

Reclaimed coal mine lands have the potential to sequester atmospheric carbon (C); however, limited information exists for the western USA coalfields. This study was carried out on two chronosequences (BA‐C3 grasses and DJ‐shrubs) of reclaimed sites at two surface coal mines to determine the effects of vegetation, soil texture, and lignin content on soil total organic carbon (TOC) accumulations. In the BA chronosequence, TOC increased over 26 years at an average rate of 0·52 Mg C ha−1 yr−1 in the 0–30 cm depth and was significantly correlated with clay content. Comparison between < 1 and 16‐year‐old stockpile soils indicated TOC content did not differ significantly. In the DJ chronosequence, TOC content in the 0–30 cm depth declined from 31·3 Mg ha−1 in 5‐year‐old soils to 23·4 Mg ha−1 in 16‐year‐old soils. The C:N ratios suggested that some (up to 2·0 per cent) of the TOC was potentially derived from coal particles in these reclaimed soils. Soil total N (TN) contents followed a similar trend as TOC with TOC and TN concentrations strongly correlated. Lignin contents in TOC of all reclaimed soils and topsoil stockpiles (TSs) were higher than that of nearby undisturbed soils, indicating the recalcitrant nature of TOC in reclaimed soils and/or possibly the slow recovery of lignin degrading organism. Results indicated that TOC accumulations in DJ were largely controlled by its composition, particular lignin content. In BA sites TOC accumulation was strongly influenced by both clay and lignin contents. Copyright © 2008 John Wiley & Sons, Ltd.
Stimuli‐Responsive Polymersomes as Nanocarriers for Drug and Gene Delivery
Authors: Onaca Ozana , Enea Ramona , Hughes David W. , Meier Wolfgang
Published: December 2008

Polymeric formulations (micelles, vesicles etc.) have emerged as versatile drug carriers due to their increased stability, site specificity, blood circulation resistance and thus overall potential therapeutic effects compared to liposomes. Furthermore, stimuli‐responsive systems have been developed whose properties change after applying certain external triggers. Polymersomes are mainly composed of amphiphilic block copolymers that are held together in water due to strong physical interactions between the insoluble hydrophobic blocks, thus forming a bilayer morphology or, in the case of triblock copolymers, a bilayer‐like morphology. Formation and destabilization of these assemblies is a consequence of external stimuli (temperature, pH, oxidation/reduction conditions etc.). This review focuses on recent developments concerning stimuli‐ responsive polymersomes made of amphiphilic block copolymers and their potential applications within the biomedical field.

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Preparation and Properties of Cyclodextrin/PNIPAm Microgels
Authors: Liu Yu‐Yang , Yu Yu , Tian Wei , Sun Le , Fan Xiao‐Dong
Published: December 2008

A two‐stage precipitation polymerization in aqueous solution was used to prepare β‐cyclodextrin/poly(N‐isopropylacrylamide) (β‐CD/PNIPAm) core–shell microgels. At the first stage, core microgels with CD moieties were synthesized by precipitation copolymerization of N‐isopropylacrylamide (NIPAm) with a monovinyl β‐CD monomer. At the second stage, using the core particles as seeds, PNIPAm shell were further added onto the seeds by NIPAm polymerization. The microgels were characterized by means of Zetasizer Nano‐ZS dynamic light scattering, TEM, IR, NMR, DSC, and TGA measurements. Using paeonol as a model drug molecule, the release behaviors of the microgels were investigated. The result indicates that the core–shell microgels could respond to change in temperature. Furthermore, the release of paeonol was related to supramolecular inclusion behavior of β‐CD and temperature sensitivity of PNIPAm.

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Hybrid Multicomponent Hydrogels for Tissue Engineering
Authors: Jia Xinqiao , Kiick Kristi L.
Published: December 2008

Artificial ECMs that not only closely mimic the hybrid nature of the natural ECM but also provide tunable material properties and enhanced biological functions are attractive candidates for tissue engineering applications. This review summarizes recent advances in developing multicomponent hybrid hydrogels by integrating modular and heterogeneous building blocks into well‐defined, multifunctional hydrogel composites. The individual building blocks can be chemically, morphologically, and functionally diverse, and the hybridization can occur at molecular level or microscopic scale. The modular nature of the designs, combined with the potential synergistic effects of the hybrid systems, has resulted in novel hydrogel matrices with robust structure and defined functions.

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Macromol. Biosci. 1/2009
Authors: Feng Yakai , Behl Marc , Kelch Steffen , Lendlein Andreas
Published: December 2008

Cover: The cover art illustrates the shape‐memory effect of a multiblock copolymer with poly(ε‐caprolactone) and poly(iso‐butylmorpholin dione) segments on two levels: the macroscopic shape recovery from the temporary shape (“stripe”) at 25°C (blue colour) to the permanent shape (“corkscrew”) at 60°C (red colour) as well as the changes of the morphology represented by AFM phase images (back image and small inset). Further details can be found in the article by Y. Feng, M. Behl, S. Kelch, A. Lendlein* on page 45.
Melt Mixing of Ethylene/Butyl Acrylate/Glycidyl Methacrylate Terpolymers with LDPE and PET
Authors: Benhamida Aida , Kaci Mustapha , Cimmino Sossio , Silvestre Clara , Duraccio Donatella
Published: December 2008

The chemical modification by melt‐mixing of an EBAGMA terpolymer with LDPE and PET was investigated with the aim to use these EBAGMA/LDPE and EBAGMA/PET blends (in equal weight quantities) as compatibilizer master batches to improve the compatibility of the LDPE/PET system. It is shown that when the EBAGMA terpolymer is melt blended with LDPE, almost 40% of the initial amount of EBAGMA is linked to the LDPE backbone. In contrast, in the case of EBAGMA/PET, FT‐IR spectra indicate the total reactivity between the two components through the reaction of the epoxy group of EBAGMA with the PET terminal groups. SEM analysis shows that both master batches present two well‐interconnected phases.

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Fourier algebras on locally compact hypergroups
Authors: Bami M. Lashkarizadeh , Pourgholamhossein M. , Samea H.
Published: December 2008

In the present paper we introduce a new definition for the Fourier spaceA(K) of a locally compact Hausdorff hypergroupKand prove that it is a Banach subspace ofB(K). This definition coincides with that of Amini and Medghalchi in the case whereKis a tensor hypergroup, and also with that of Vrem which is given only for compact hypergroups. We prove thatAp(K)* =PMq(K), whereqis the exponent conjugate top, in particularA(K)* =VN(K). Also we show that for Pontryagin hypergroups,A(K) =L2(K) *L2(K) =F(L1($ \hat K $)), whereFstands for the Fourier transform on$ \hat K $. Furthermore there is an equivalent norm onA(K) which makesA(K) into a Banach algebra isomorphic withL1($ \hat K $). (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parabolic Littlewood–Paley operators
Authors: Xue Qingying , Ding Yong , Yabuta Kôzô
Published: December 2008

In this paper, weak (1,1) and Lp estimates for the parabolic Littlewood–Paley operators on some homogeneous spaces are established, which are extensions of known results. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A note on Schatten‐class membership of Hankel operators with antiholomorphic symbols on generalized Fock‐spaces
Authors: Schneider Georg
Published: December 2008

In this paper we investigate Hankel operators with anti‐holomorphic L2‐symbols on generalized Fock spaces Am2 in one complex dimension. The investigation of the mentioned operators was started in [4] and [3]. Here, we show that a Hankel operator with anti‐holomorphic L2‐symbol is in the Schatten‐class Sp if and only if the symbol is a polynomial with degree N satisfying 2N < m and p > . The result has been proved independently before in the recent work [2], which also considers the case of several complex variables. However, in addition to providing a different proof for the result the present work shows that the methodology developed in [4] and [3] can be adopted in order to work to characterize Schatten‐class membership. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microwave‐Sensitive Foamable Poly(ionic liquids) Bearing tert‐Butyl Ester Groups: Influence of Counterions on the Ester Pyrolysis
Authors: Amajjahe Sadik , Ritter Helmut
Published: December 2008

Several poly(ionic liquids) have been synthesized based on poly(1‐vinyl‐3‐tert‐butoxycarbonylmethylene imidazolium) salts with different counterions to investigate the tert‐butyl ester pyrolysis of these compounds. It is found that the counterions strongly influence the temperature of the pyrolysis. The pyrolysis temperature shifts to higher or lower temperatures depending on the nature of the counterions. The use of microwave irradiation was employed to accelerate the gas release because of the high dipolar interaction of amorphous salts with microwaves. The result of these reactions is the formation of organic foams that could be of industrial interest.

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Polyaniline Fan‐Like Architectures of Rectangular Sub‐Microtubes Synthesized in Dilute Inorganic Acid Solution
Authors: Zhou Chuanqiang , Han Jie , Guo Rong
Published: December 2008

Rectangular‐tube‐based fan‐like polyaniline has been readily fabricated by the oxidation polymerization of low‐concentration aniline in dilute HCl aqueous solution for the first time. Different from the conventional polymerization that proceeds in concentrated acidic solution (to produce nanofibers), this synthesis was conducted in dilute inorganic acid solution at room temperature and created polyaniline hierarchical fan‐like architectures. The morphological evolution of the product has been followed with respect to the reaction time, based on which conceivable interpretations of the formation of rectangular tubes and their assembly into fan‐like architectures are given. Other inorganic acids (HNO3, H2SO4, and H3PO4) with low concentrations have been used to replace HCl in the reaction system to validate the adaptability of this approach in this report.

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Effect of Added Homopolymer on the Hexagonal Phase Formed by Cylindrical Block Copolymer Micelles in a Selective Solvent
Authors: Abbas Sayeed , Cowman Christina D. , Lodge Timothy P.
Published: December 2008

The effect of addition of A homopolymer chains to HEX phases formed by cylindrical micelles obtained by dissolving an AB diblock copolymers in an A selective solvent was investigated. The following general trends were observed: (i) order–order transitions from HEX → Gyroid (G) → Lamellae (LAM); (ii) the inter‐cylinder spacing of the HEX phase increased; (iii) when the homopolymer molecular weight and concentration was high, macrophase separation of the system occurred. The A homopolymer chains do not mix significantly with the A domain of the diblock due to excluded volume interactions, causing the corona chain brush to contract. As a result, order–order transitions that reduce the interfacial curvature are observed.

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Catalytic Polymerizations of Hydrophobic, Substituted, Acetylene Monomers in an Aqueous Medium by Using a Monomer/Hydroxypropyl‐β‐cyclodextrin Inclusion Complex
Authors: Ding Lei , Jiao Xuefeng , Deng Jianping , Zhao Weiguo , Yang Wantai
Published: December 2008

Ten hydrophobic, substituted, acetylene monomers were examined as to their abilities to form an inclusion complex with hydroxypropyl‐β‐cyclodextrin (HPCD). Only the monomers with suitable substitutents were found to form the monomer/HPCD complex, which was identified by NMR, FTIR, and UV‐vis spectroscopy. Polymerizations of the monomers were successfully carried out in aqueous solution by using the prepared monomer/HPCD inclusion complex and by using a water‐soluble Rh‐based catalyst, [Rh(cod)2BF4] or [Rh(nbd)(H2O)OTs]. Such polymerizations provided high‐yield (>90%) polymers with a cis content of approximately 100%. The as‐prepared polymers could take an ordered helical conformation, just like their counterparts obtained in organic solvents.

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In situ Synthesis of Magnetic Iron Oxide Nanoparticles in Thermally Responsive Alginate‐Poly(N‐isopropylacrylamide) Semi‐Interpenetrating Polymer Networks
Authors: Hernández Rebeca , Mijangos Carmen
Published: December 2008

A novel semi‐interpenetrating polymer network based on alginate and poly(N‐isopropylacrylamide) (PNiPAAm) has been synthesized that shows response to temperature and magnetic fields. Highly homogeneous porous hydrogels are obtained by copolymerizing N‐isopropylacrylamide and bis‐acrylamide in the presence of an aqueous alginate solution. The synthesis of magnetic iron oxides by in‐situ oxidation of iron cations coordinated to the alginate network results in a hydrogel with an enhanced deswelling rate with respect to pure PNiPAAm.

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Quartz Crystal Microbalance Studies on Conformational Change of Polymer Chains at Interface
Authors: Zhang Guangzhao , Wu Chi
Published: December 2008

The conformation of polymers at interface profoundly influences the interfacial properties. Quartz crystal microbalance with dissipation (QCM‐D) is a newly developed technique to detect polymer behavior at interface in real time. In this article, we mainly review our QCM‐D studies. Our focus is on temperature induced collapse and swelling of tethered polymer chains, pancake‐to‐brush transition and mushroom‐to‐brush of polymer chains.

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Orientation of Syndiotactic Polystyrene Crystallized in Cylindrical Nanopores
Authors: Wu Hui , Wang Wei , Huang Yan , Su Zhaohui
Published: December 2008

Syndiotactic polystyrene (sPS) nanorods with different diameters have been prepared by using anodic aluminum oxide templates, and the orientation of the sPS crystals in the nanorods has been investigated by FT‐IR spectroscopy. It is found that the c axis of the β′ crystals preferentially oriented perpendicular to the axis of the nanorod, and the degree of orientation is lower as the diameter of the nanorod decreases. This unexpected result is attributed to nuclei formed at the surface of the nanopores and their subsequent growth, in addition to the preferential growth compatible with the pore direction by the nuclei formed in the bulk film and in the nanorods.

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Monte‐Carlo Method for Simulations of Ring Polymers in the Melt
Authors: Vettorel Thomas , Reigh Shang Yik , Yoon Do Y. , Kremer Kurt
Published: December 2008

A detailed analysis of the efficiency of a Monte‐Carlo (MC) method employing non‐local moves for simple lattice ring polymers is presented. While the introduction of kink‐translocation moves for linear chains results in the expected speedup by a factor of the order of the number of sites, this is significantly reduced for a melt of rings.

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Enhanced One‐ and Two‐Photon Excitation Emission of a Porphyrin Photosensitizer by FRET from a Conjugated Polyelectrolyte
Authors: Wu Chuanliu , Xu Qing‐Hua
Published: December 2008

Porphyrin‐based systems are widely used as photosensitizers for photodynamic therapy, photocatalysis, and drug release. Strategies to enhance one‐ or two‐photon excitation emission of porphyrin sensitizers have been of great interest and significance. Here we report an electrostatic assembly, which comprises a cationic conjugated polyelectrolyte, PFP, and a negatively charged hematoporphyrin (HP). An enhancement of over 9‐fold in the HP emission intensity for one‐photon excitation Förster resonance energy transfer (FRET), and an enhancement factor of 30‐fold for two‐photon excitation FRET were obtained. This electrostatic assembly can be easily modified in the future to construct DNA‐ or protein‐programmed enhancement of porphyrin emission, which will be of great interest in porphyrin‐based applications.

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Theoretical Derivation of the Molecular Weight Distribution of End‐Capped Linear Condensation Polymers
Authors: Knoester Henk
Published: December 2008

End‐capped, low molecular weight polymers have found numerous practical applications. By providing the end‐capper molecules with specific chemical functionality, the polymer material can be equipped with a desired chemical behavior for product application or polymer processing. Using probabilistic methods, formulas are derived for calculating the target molecular weight distribution and its averages for the case of linear condensation polymerization. The formulas are generally applicable, allowing for arbitrary amounts of monofunctional monomers or end‐capper molecules affecting either one or both functional groups involved in the polymerization process.

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Complexity as a constraint on firm expansion within and across industries
Authors: Hutzschenreuter Thomas , Guenther Fabian
Published: December 2008

With this paper, we want to shed light on factors influencing a firm's rate of expansion. We argue that expansion is a complex task and complexity associated with expansion projects in one period can negatively impact rate of expansion in the following period. Moreover, we argue that firm portfolio complexity also slows down further expansion. Using longitudinal data on the expansion path of 91 German companies, we show that added product scope of expansion and degree of internationalization characterizing expansion in one period as well as level of product and international diversity have a significant impact on slowing down rate of expansion in the subsequent period. Copyright © 2008 John Wiley & Sons, Ltd.
Design of a compact CPW bandpass filter used for UWB application
Authors: Ye Chang‐Sin , Su Yan‐Kuin , Weng Min‐Hang , Hon‐Kuan  , Syu Jheng‐Jie
Published: December 2008

In this paper, design of a compact coplanar‐waveguide (CPW) bandpass filter (BPF) for low band (3–5 GHz) of ultra wide band (UWB) application is presented. The filter has design freedoms to obtain the proper bandwidth by tuning the frequencies of the transmission zeros at the passband edge. The equivalent circuit of the filter is also obtained. The designed filter exhibits a good lower stopband with rejection greater than 20 dB below 2.95 GHz, which can block the interference of other wireless communication system below 3 GHz. The designed CPW‐BPF is investigated numerically and experimentally. Measured results show a good agreement with the simulated analysis. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 298–300, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24028
Highly selective bandpass filters using broadside‐coupled coplanar waveguide directional couplers
Authors: Sánchez‐Soriano Miguel Á. , Torregrosa‐Penalva Germán , Bronchalo Enrique , Coves Ángela
Published: December 2008

In this work, a new type of wideband coplanar bandpass filter with sharp skirts and large stopband is proposed. The filter exhibits a flat response in the passband, and a steep slope and a high rejection in the stopband. The filter design is based on the use of a broadside‐coupled (BC) coplanar‐waveguide (CPW) directional coupler as a transversal filtering section (TFS). This is performed by conveniently loading two ports of the coupler with shunt stubs, so that the signals in the output port interfere in a way that a bandpass filter response is obtained. The suggested filter scheme has been validated experimentally throughout the design, fabrication, and measurement of a wideband coplanar bandpass filter centered at 2.0 GHz, formed by two TFS connected in cascade. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 294–298, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24029
Analysis of stacked V‐slot loaded patch antenna for wideband application
Authors: Ansari J. A. , Singh Prabhakar , Dubey Satya Kesh , Khan R. U. , Vishvakarma Babau R.
Published: December 2008

The analysis of V‐slot loaded antenna stacked with simple patch is carried out using equivalent circuit model. It is found that stacked patch antenna exhibits enhanced bandwidth that depends on various dimensions of the V‐slot. The proposed theoretical results are compared with simulated and reported experimental results which are in good agreement. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 324–330, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24031
Compact 3‐D on‐wafer radiation pattern measurement system for 60 GHz antennas
Authors: Ranvier Sylvain , Kyrö Mikko , Icheln Clemens , Luxey Cyril , Staraj Robert , Vainikainen Pertti
Published: December 2008

This article presents a quasi full 3‐D on‐wafer radiation pattern measurement system for 60 GHz antennas. The measurement of an omnidirectional antenna is reported and shows promising results. The radiation of the probe itself as well as the effects of a connector feeding the antenna are also studied. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 319–324, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24034
Method for the design of low‐loss suspended stripline directional couplers with equalized inductive and capacitive coupling coefficients
Authors: Wincza Krzysztof , Gruszczynski Slawomir
Published: December 2008

Design of directional couplers in an inhomogeneous suspended stripline dielectric structure has been comprehensively investigated. A new design procedure of coupled‐line directional couplers has been proposed in which the equalization of inductive and capacitive coupling coefficients is achieved simultaneously with matching to the desired characteristic impedance and, therefore, the conditions of ideal coupler realization can be approached. To achieve that, a method of modification of the capacitive coupling coefficient in which shunt capacitances are added to coupled lines has been used. The proposed design procedure has been successfully applied to the design of a 3‐dB directional coupler. Results of both calculations and measurements are presented. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 315–319, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24035
Cross‐Vivaldi antenna for breast tumor detection
Authors: Zhang Jingjing , Fear Elise C. , Johnston Ronald H.
Published: December 2008

Observation of cross‐polarized reflections has been proposed for radar‐based breast tumor detection. In this article, a novel cross‐Vivaldi antenna is designed and investigated for this application. The antenna performance is examined over the frequency range of 2.2–5.4 GHz. Results obtained through simulations and experiments demonstrate the ability of the antenna to detect tumors in three‐dimensional (3D) breast models. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 275–280, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24037
Novel metallodielectric electromagnetic bandgap structure
Authors: Kelly James R. , Seager Rob D.
Published: December 2008

This article is concerned with a novel microstrip EBG structure, formed by etching a shape into the signal line. Previous publications announced a lumped‐element equivalent circuit for the structure. This article gives simple equations for computing the equivalent circuit element values. The article also announces an effective EBG low‐pass filter. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 311–315, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24038
Lattice‐type balun with enhanced phase characteristic based on organic system on a package technology
Authors: Park Jong C. , Park Jae Y.
Published: December 2008

In this article, lattice‐type LC balanced‐to‐unbalanced (balun) embedded into a multilayered organic package substrate have been designed, fabricated, and characterized for low cost and small size WLAN and Bluetooth applications. To minimize the phase error of the embedded baluns, LC resonator was utilized instead of shunt capacitor used at conventional lattice‐type balun, furthermore, the quality factors and packaging efficiencies of embedded inductors are maximized by using vertically stacked circular geometry. It has the insertion loss of 0.7 dB, return loss of 21 dB, phase imbalance of 5°, and frequency band width ranged from 2.3 to 2.55 GHz. The fabricated balun was significantly reduced in size and volume by using the vertically stacked spiral inductors and MIM capacitors with BTO high DK film. It has a size of 2.7 ×2.5 ×0.66 mm (height). It is promising for various RF system on a package (SOP) products with multi functionalities, small size, and low cost. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 399–402, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24041
A compact dual‐element antenna array for adaptive MIMO system
Authors: Wang Xuan , Du Zhengwei , Gong Ke
Published: December 2008

A novel compact dual‐element antenna array is proposed for adaptive MIMO system. By four embedded PIN diodes in the feeding network, the antenna array has three different working states. It can operate as a dual‐element antenna array or work as a single antenna while the unselected antenna is terminated to a lumped matched resistor. As a dual‐element antenna array, it has a −10 dB impedance bandwidth of 595 MHz covering UMTS band with mutual coupling lower than −15 dB in the whole band. The measured radiation patterns show that the radiation property of the selected antenna keeps steady no matter the other antenna is selected or not. The proposed antenna array can achieve antenna selection scheme to adapt to the time‐varying channel conditions. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 348–351, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24044
Low power consumption and high gain ultra‐wide‐band low noise amplifier
Authors: Huang Shou‐Chien , Tsai Cheng‐Hsiu , Hsin Yue‐Ming
Published: December 2008

A low power consumption and high gain ultra‐wide‐band (UWB) low noise amplifier (LNA) utilizing a common‐gate stage connected with a common‐source stage by using current‐reused structure is proposed. The implemented LNA exhibits a maximum power gain of 14.2 dB with a total (core) power consumption of 7.2 mW (3.8 mW) under a 1.5 V power supply. A minimum noise figure of 4.1 dB was obtained within 3‐dB bandwidth of 2.7–8.2 GHz. The proposed UWB LNA presents the highest ratio of the power gain to power consumption among the compared papers. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 382–384, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24047
Analysis and applications of a novel cylindrical dielectric core multiconductor transmission‐line structure
Authors: Faria Jose A. Brandão
Published: December 2008

A novel inhomogeneous multiconductor transmission line (MTL) device consisting of a solid cylindrical dielectric core with N + 1 equidistant cylindrical thin wires running along the core's peripheral surface, parallel to the core axis, is examined here. The frequency domain properties of the novel structure are revealed with the help of standard MTL modal analysis techniques. A particular application, for example with four wires, is developed by enforcing a full short‐circuit condition at the far end of the line. The input impedance of the device is obtained by considering several options for the wire connections at the near end of the line. Computed results concerning the MTL device show that the proposed structure exhibits sharp selectivity features in the frequency domain. Results are interpreted physically by making use of equivalent two‐conductor line models, which lead to estimated parameter values in excellent agreement with the computed ones. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 374–382, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24049
Reconfigurable scan‐beam hollow patch reflectarray antenna loaded with tunable capacitor
Authors: Hajian M. , Kuijpers B. , Buisman K. , Akhnoukh A. , Plek M. , de Vreede L. C. N. , Zijdeveld J. , Ligthart L. P.
Published: December 2008

In this article, the design concept of an active reconfigurable reflectarray antenna has been proposed and tested. The elementary radiators are hollow patch element loaded with varactor‐diode device in which the reflected phase can be varied. This phase alteration is based on the variation of the diode capacitance which can be achieved by varying the biasing voltage of the active varactor device. By activating these varactor devices, the phase of each antenna element in the array configuration can be adopted dynamically, and consequently, its radiation beam direction can be reconfigured. The advantage of the MEMS switches is the complexity of the integration and continuing beam scanning capability. The reflectarray incorporating active elements has been built and tested at 6.0 GHz. Narrow band multifrequency shared aperture is demonstrated theoretically and experimentally. The performance of the proposed active antenna is excellent, which pioneers the design of arbitrarily reconfigurable antennas. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 367–374, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24050
Ultra‐wideband antenna design using FDTD and double population genetic algorithm
Authors: Zhao Guo‐Hua , Shen Wen‐Hui , Wu Ming‐Liang
Published: December 2008

In this article, a method for the computer aided design of ultra‐wideband (UWB) printed planar monopoles using double population genetic algorithm and finite‐difference time domain (FDTD) is presented. A novel UWB antenna is obtained successfully. The measured return loss shows an impedance bandwidth of 12.75 GHz from 2.75 to 15.5 GHz for VSWR < 2. Moreover, the designed antenna has a good radiation characteristic with peak gains ranging from 0.9 to 6.97 dBi against operating frequencies. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 361–364, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24052
Quadrature and eight‐phase VCOs implemented with SiGe injection locked frequency dividers
Authors: Jang Sheng‐Lyang , Liu Cheng‐Pin , Lee Chien‐Feng , Hsue Ching‐Wen
Published: December 2008

This article proposes a new technique for designing multi‐phase voltage controlled oscillators (VCOs), which were implemented in the standard TSMC 0.35 μm SiGe 3P3M BiCMOS process. The quadrature voltage‐controlled oscillator (QVCO) consists of two direct‐ injection locked frequency dividers (ILFDs) with a tail MOSFET. The 2nd harmonic frequency component at the drain node of tail transistor in one ILFD is injected to the gate of injection MOSFET in the other ILFD to couple the two independent ILFDs. The eight‐phase VCO is also designed with similar technique to couple four differential VCOs. At the supply voltage of 3.0 V, the output phase noise of the QVCO is −118.22 dBc/Hz at 1 MHz offset frequency from the carrier frequency of 2.28 GHz, and the figure of merit is −173.25 dBc/Hz. At the supply voltage of 3.0 V, the total power consumption is 14.4 mW. At the supply voltage of 3.0 V, the output phase noise of the eight‐phase VCO is −116.14 dBc/Hz at 1 MHz offset frequency from the carrier frequency of 2.92 GHz, and the figure of merit is −171.3 dBc/Hz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 395–398, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24053
The research of mix Raman and EDFA amplifier recycling residual Raman pump for amplifier gain efficiency improvement
Authors: Lin Hsiu‐Sheng , Lai Po‐Chou
Published: December 2008

We propose and demonstrate a novel type of mix Raman and Erbium Doped Fiber Amplifier (EDFA) to recycle the residual Raman pump for enhancing the gain efficiency of power. The mix amplifier is to implement the residual Raman pump from the Stimulated Raman Scattering (SRS) of Raman fiber amplifier (RFA), to be recycled in the Erbium doped fiber (EDF) as the pump of the Erbium doped fiber amplifier (EDFA) [Dai et al., IEEE Photon Technol Lett 8 (1996), 1713–1715.1]. The proposed mix amplifier system structure has only one pump source for Raman amplification, and residual Raman pump after the Dispersion compensating fiber (DCF) is recycled for erbium doped fiber as the secondary signal amplification. The proposed mix amplifier structure can improve the total gain efficiency by 19.3 dB, compared with the performance of the only one Raman amplifier. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 358–361, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24055
Temperature‐insensitive refractive index sensor based on tilted fiber Bragg grating
Authors: Miao Yinping , Liu Bo , Tian Shuang , Zhao Qida
Published: December 2008

Short‐period fiber Bragg gratings with gratings planes tilted at an angle 8° corresponding to the fiber axis show core mode and a large number of cladding‐mode resonances in transmission. The differences between the cladding‐mode resonance and the core‐mode resonance are used to detect the variation of the surrounding refractive index; this refractive index sensor is immune to temperature effects by experimental demonstrations. After the cladding of the tilted fiber, Bragg grating was etched by the hydrofluoric, TFBGs with different diameters and different‐order cladding modes were investigated; the sensitivity of a TFBG to the external index can be significantly improved by reducing the cladding radius. Enhanced sensitivity and accuracy are achieved when the changes between 1.333 and 1.4532. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 479–483, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24057
A reduced‐size branch‐line coupler for improved LDMOS balanced power amplifiers
Authors: Draskovic Drasko , Koulouzis H. , Budimir D.
Published: December 2008

This article discusses the application of a reduced‐size branch‐line coupler in the design of a LDMOS class‐AB balanced power amplifier at a center frequency of 2.14 GHz. In the proposed balanced configuration, at center frequency a size reduction, improved intermodulation distortion level by 7 dB, and power added efficiency by 5% are achieved, comparing with the balanced configuration with Wilkinson couplers. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 445–448, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24058
Analysis of conductor‐backed coplanar waveguides using adaptive‐network‐based fuzzy inference system models
Authors: Yildiz Celal , Guney Kerim , Turkmen Mustafa , Kaya Sabri
Published: December 2008

A method based on adaptive‐network‐based fuzzy inference system (ANFIS) is presented for the quasi‐static analysis of conductor‐backed coplanar waveguides. The ANFIS is a class of adaptive networks which are functionally equivalent to fuzzy inference systems. Four optimization algorithms, hybrid learning, genetic, simulated annealing, and least‐squares, are used to determine optimally the design parameters of the ANFIS. The results of ANFIS are compared with the results of experimental works, quasi‐static and full‐wave spectral domain approaches, conformal mapping technique, and a commercial electromagnetic simulator IE3D. The results of ANFIS models are in very good agreement with the results of other methods and experimental works. When the performances of ANFIS models are compared with each other, the best result is obtained from the ANFIS model trained by the hybrid learning algorithm. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 439–445, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24059
Erratum: Extreme performance TEM horn
Authors: Malherbe J. A. G.
Published: December 2008

Originally published Microwave Opt Technol Lett 50:2121–2125, 2008. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 583, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24060
Low profile and compact size coplanar UWB antenna working from 2.8 GHz to over 40 GHz
Authors: Naeem Khan Salman , Shuai Zhang , He Sailing
Published: December 2008

A square monopole coplanar antenna with a circular base is proposed for ultra wideband (UWB) communications. The design parameters are analyzed and optimized to obtain a good performance and the measured return loss below −10 dB is from 2.8 to over 40 GHz. The proposed antenna has advantages of low profile, small size, UWB, and omni‐directional pattern. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 408–411, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24062
A novel polarization reconfigurable ring‐slot antenna with frequency agility
Authors: Zhao Yu‐Long , Jiao Yong‐Chang , Zhao Gang , Weng Zi‐Bin , Zhang Fu‐Shun
Published: December 2008

A novel reconfigurable ring‐slot antenna with switchable polarization and frequency agility is presented. Circular polarization (CP) radiation of the proposed antenna is achieved by introducing proper asymmetry in the ring‐slot structure and feeding the ring slot using a microstrip line at 45° from the introduced asymmetry. Two diodes are used to reconfigure the structure of the ring slot. Switching between right‐hand and left‐hand CP is achieved by turning the diodes on or off and the two CP modes are operated at different frequencies. Moreover, the antenna has a simple structure, which is easier to be fabricated. An antenna prototype is implemented and the measured results are shown. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 540–543, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24064
Analysis of cladding modes in an asymmetric dual‐core fiber
Authors: Chan Florence Y. M. , Yasumoto Kiyotoshi , Sharma Enakshi K.
Published: December 2008

A theoretical analysis of the cladding modes is presented for an asymmetric dual‐core fiber that consists of a primary core near the fiber axis and a secondary core. Numerical examples are given to demonstrate that the approximation of a two‐layer fiber geometry is inadequate to describe the accurate modal properties of the cladding modes. It is shown that the field distributions of the cladding modes are dependent on the azimuthal angle under the presence of two cores. The maximum field intensities are located away from the fiber axis with a shift in the local maxima in the primary core toward the secondary core. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 507–510, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24066
Erratum: Application of the tree‐cotree splitting for improving matrix conditioning in the full‐wave finite‐element analysis of high‐speed circuits
Authors: Lee Shih‐Hao , Jin Jian‐Ming
Published: December 2008

Originally published Microwave Opt Technol Lett 50:1476–1481, 2008. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 582, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24068