bluuebunny/crossref_metadata_2025 huggingface dataset:
Directed information flow—A model free measure to analyze causal interactions in event related EEG‐MEG‐experiments
Authors: Hinrichs Hermann , Noesselt Toemme , Heinze Hans‐Jochen
Published: March 2007

In a study that combined event related potential (ERP) and magnetic field (ERMF) data, we analyzed the timing and direction of information flow between striate (S) and extrastriate (ES) cortex by applying a generalized mutual information measure (DIT for “directed information transfer”) during a visual spatial attention task. ERP and ERMF recordings showed that selective attention to stimulus arrays in one visual field enhanced late responses (around 200 ms after the stimulus presentation) that were localized in S (ERMF) and ES (ERP) cortex. The results of the DIT analysis indicate there is a significant attention related increase in the flow of information back from ES to S cortex at around 220 ms, with an associated decrease in the flow of information forward from S cortex to ES cortex. These results support the hypothesis that a feedback mechanism guides attention‐related processing in primary visual cortex and provide evidence that DIT can by used to evaluate the direction of information flow between cortical areas. Hum Brain Mapp, 2008. © 2007 Wiley‐Liss, Inc.
Structuring process to improve student outcomes
Authors: Schalock H. D.
Published: March 2007

Efforts to improve instruction in higher education are evolving at an unprecedented rate and with unprecedented promise; institutions, moreover, are adopting new approaches to instruction on an unprecedented scale.
Long‐lead seasonal rainfall forecasting using time‐delay recurrent neural networks: a case study
Authors: Karamouz Mohammad , Razavi Saman , Araghinejad Shahab
Published: March 2007

A temporal artificial neural network‐based model is developed and applied for long‐lead rainfall forecasting. Tapped delay lines and recurrent connections are two different components that are used along with a static multilayer perceptron network to design a time‐delay recurrent neural network. The proposed model is, in fact, a combination of time‐delay and recurrent neural networks. The model is applied in three case studies of the Northwest, West, and Southwest basins of Iran. In addition, an autoregressive moving average with exogenous inputs (ARMAX) model is used as a baseline in order to be compared with the time‐delay recurrent neural networks developed in this study. Large‐scale climate signals, such as sea‐level pressure, that affect the rainfall of the study area are used as the predictors in the models, as well as the persistence between rainfall data. The results of winter‐spring rainfall forecasts are discussed thoroughly. It is demonstrated that in all cases the proposed neural network results in better forecasts in comparison with the statistical ARMAX model. Moreover, it is found that in two of three case studies the time‐delay recurrent neural networks perform better than either recurrent or time‐delay neural networks. The results demonstrate that the proposed method can significantly improve the long‐lead forecast by utilizing a non‐linear relationship between climatic predictors and rainfall in a region. Copyright © 2007 John Wiley & Sons, Ltd.
Measles virus and classical Hodgkin lymphoma: No evidence for a direct association
Authors: Wilson K.S. , Freeland J.M.L. , Gallagher A. , Cosby S.L. , Earle J.A.P. , Alexander F.E. , Taylor G.M. , Jarrett R.F.
Published: March 2007

A proportion of Hodgkin lymphoma (HL) cases are causally associated with the Epstein‐Barr virus (EBV) but the aetiology of the remaining cases remains obscure. Over the last 3 decades several studies have found an association between HL and measles virus (MV) including a recent cohort study describing the detection of MV antigens in Hodgkin and Reed‐Sternberg cells, the tumour cells in HL. In the present study we looked at the relationship between history of MV infection and risk of developing HL in a population‐based, case/control study of HL. In addition we used immunohistochemistry and RT‐PCR to look for direct evidence of MV in HL biopsies. There was no significant difference in the proportion of cases reporting previous measles compared to controls in the entire data set or when young adults were considered separately. Using a robust immunohistochemical assay for MV infection, we failed to find evidence of MV in biopsies from 97 cases of HL and RT‐PCR studies similarly gave negative results. This study therefore provides no evidence that MV is directly involved in the development of HL. However, when age at first reported MV infection was investigated, significant differences emerged with children infected before school‐age having higher risk, especially of EBV−ve HL, when compared with children infected at older ages; the interpretation of these latter results is unclear. © 2007 Wiley‐Liss, Inc.
Biodegradable magnesium scaffolds: Part 1: Appropriate inflammatory response
Authors: Witte F. , Ulrich H. , Rudert M. , Willbold E.
Published: March 2007

Current tissue engineering strategies focus on the replacement of pathologically altered tissues by the transplantation of cells in combination with supportive biocompatible scaffolds. Scaffolds for tissue engineering strategies in musculoskeletal research require an appropriate mechanical stability. In recent studies, considerable attention has thus been given to magnesium alloys as biodegradable implants. The aim of this study was to characterize the biocompatibility of magnesium scaffolds by the inflammatory host response. Open porous scaffolds made of the magnesium alloy AZ91D were implanted into the distal femur condyle of rabbits and were compared to autologous bone, which was transplanted into the contralateral condyle in a 3 and 6 months follow‐up group. After 3 months, magnesium scaffolds were already largely degraded and most of the original magnesium alloy has disappeared. Concomitantly, a fibrous capsule enclosed the operation site. Histological analysis revealed that the magnesium scaffolds caused no significant harm to their neighboring tissues. This study shows that even fast degrading magnesium scaffolds show a good biocompatibility and react in vivo with an appropriate inflammatory host response. Magnesium alloy based implants are therefore a very promising approach in the development of mechanically suitable and open porous scaffolds for the replacement of subchondral bone in cartilage tissue engineering. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Compositional dependence on the in vitro bioactivity of invert or conventional bioglasses in the Si‐Ca‐Na‐P system
Authors: Lebecq I. , Désanglois F. , Leriche A. , Follet‐Houttemane C.
Published: March 2007

The bioactivity of 34 invert or conventional glasses in the P‐free and P‐containing Si‐Ca‐Na system was evaluated by examining the in vitro HydroxyCarbonateApatite (HCA) formation time. The silica content in the glasses varies between 39.48 and 55 mol %. The surfaces of glasses after soaking in simulated body fluid at 37°C were analyzed by Fourier transform infraRed spectroscopy and scanning electron microscopy coupled with energy dispersive spectroscopy. To understand the HCA formation mechanism, the modification of the glass surface structure was studied. The aim was to understand, in the Si‐Ca‐Na‐P system, the function of each constituent on glass reactivity. It was noted that the bioactivity of Si‐Ca‐Na‐P glasses depends on the P ratio. One of the P‐free glasses is as bioactive as the Hench's Bioglass® noted 45S5, because it needs 12 h to develop HCA as for Hench's one. In the quaternary system, some of the P‐rich and Na, Si‐poor glasses are more bioactive than 45S5 (6–10 h to obtain HCA). Two phosphorus effects were observed: the repolymerization of the silicate network and the formation of phosphate‐modifier cation complexes. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Biodegradable magnesium scaffolds: Part II: Peri‐implant bone remodeling
Authors: Witte F. , Ulrich H. , Palm C. , Willbold E.
Published: March 2007

In this study, histomorphometrical parameters of the peri‐implant bone remodeling around degrading open‐porous scaffolds made of magnesium alloy AZ91D were investigated and compared with the peri‐implant bone remodeling around an autologous bone transplant in the contralateral side in a rabbit model after 3 and 6 months. Osteoblast activity was displayed by collagen I (alpha 2) mRNA in situ hybridization. Major scaffold degradation was completed within 3 months after implantation showing no osteolysis around the scaffolds, both after 3 and 6 months. Enhanced formation of unmineralized extracellular matrix and an enhanced mineral apposition rate adjacent to the degrading magnesium scaffolds were accompanied by an increased osteoclastic bone surface, which resulted in higher bone mass and a tendency to a more mature trabecular bone structure around the magnesium scaffolds compared to the control. These results show that even fast‐degrading magnesium scaffolds induce extended peri‐implant bone remodeling with a good biocompatibility. In summary, this study shows that degrading magnesium scaffolds promote both bone formation and resorption in a rabbit model and are therefore very promising candidates for the development of novel implants in musculoskeletal surgery. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
ERM is expressed by alveolar epithelial cells in adult mouse lung and regulates caveolin‐1 transcription in mouse lung epithelial cell lines
Authors: Kathuria Hasmeena , Cao YuXia , Hinds Anne , Ramirez Maria I. , Williams Mary C.
Published: March 2007

We previously identified an Ets cis‐element in the mouse caveolin‐1 promoter that is selectively activated in lung epithelial (E10), but not lung endothelial murine lung endothelial cell line (MFLM‐4), cell lines and therefore appears important for differential, cell‐specific caveolin‐1 transcription. In the present study, we demonstrate that immunostaining of adult mouse lung detects the ETS protein Ets‐related molecule (ERM PEA3) in distal lung epithelium in alveolar type I and II cells, but not in bronchial epithelium or lung endothelial cells. We tested ERM and polyomavirus enhancer activator 3 (PEA3) for their ability to increase endogenous caveolin‐1 transcripts and to activate caveolin‐1 promoter fragments containing the −865 Ets cis‐element. Chromatin immunoprecipitation (ChIP) assays show that both ERM and PEA3 bind to the caveolin‐1 promoter in murine E10, but not MFLM‐4, cells. Normalized luciferase activities show that only ERM activates the caveolin‐1 promoter in E10 cells, but neither protein enhances promoter activity in MFLM‐4 cells. Mutation of the Ets site blocks ERM‐mediated promoter activation in E10 cells. Furthermore, overexpression of ERM increases the cellular content of caveolin‐1 mRNA and protein, in E10, but not MFLM‐4, cells. The effects of PEA3 on the cellular content of endogenous caveolin‐1 expression are variable. These results demonstrate that ERM is involved in caveolin‐1 regulation in a murine lung epithelial, but not lung endothelial cell line. We conclude that transcriptional regulation of caveolin‐1 differs markedly between lung epithelial and endothelial cell lines, perhaps explaining why the onset of caveolin‐1 expression differs in epithelial and endothelial cells during lung development. J. Cell. Biochem. 102: 13–27, 2007. © 2007 Wiley‐Liss, Inc.
Inhibition of neuronal migration by JONES antibody is independent of 9‐O‐acetyl GD3 in GD3‐synthase knockout mice
Authors: Yang Chia‐Ron , Liour Sean S. , Dasgupta Somsankar , Yu Robert K.
Published: March 2007

It has been shown previously that the migration of granule neurons in neonatal cerebellum can be inhibited by a monoclonal antibody (Mab) JONES. Because the inhibition is presumed to be mediated through binding of the JONES antibody to 9‐O‐acetyl GD3, we used GD3‐synthase knockout (GD3S−/−) mice that do not express 9‐O‐acetyl GD3 and also have no detectable defect in brain development, to examine the mechanism of the inhibitory effect. We found no difference between the migration of granule neurons in the neonatal cerebellar explant culture in GD3S−/− mice and in wild‐type mice. Addition of the Mab JONES, but not Mab R24 or A2B5, in the culture medium blocked the neuronal migration in the explant culture of the wild‐type mice. The inhibitory effect of Mab JONES was also observed, however, in the explant culture of GD3S−/− mice. Immuno‐HPTLC analysis showed at least two JONES‐positive glycolipids bands in the lipid extract of GD3S+/+ mice, and none was detected in that of GD3S−/− mice. Western blot analysis of the cerebellum homogenate of wild‐type and GD3S−/− mice identified at least 3 JONES‐positive protein bands, one of which is β1‐integrin. Because the JONES antibody also blocked neuronal migration in the cerebellar explant culture of GD3S−/− mice that do not express 9‐O‐acetyl‐GD3, it suggested an alternative mechanism for the inhibitory effect of the antibody, at least in the GD3S knockout mice, and the inhibitory effect of the JONES antibody on neuronal migration could be mediated through its binding to β1‐integrin. © 2007 Wiley‐Liss, Inc.
Determination of anti‐inflammatory drugs and estrogens in water by HPLC with UV detection
Authors: Stafiej Anna , Pyrzynska Krystyna , Regan Fiona
Published: March 2007

An analytical method based on LC and UV detection has been developed for the determination of anti‐inflammatory compounds and estrogens in water samples. The drugs investigated were diclofenac, ketoprofen, ibuprofen, naproxen, clofibric acid, estriol, 17β‐estradiol, estrone and ethynylestradiol. The detection limits were in the range of 6–74 μg/L and 0.041–0.16 mg/L for acidic pharmaceuticals and estrogens, respectively, using narrow‐bore C18 analytical column. Analyte enrichment from water samples was achieved by SPE procedure using polymeric Strata‐X cartridges. Average recoveries obtained from 2.5 L of surface water sample were in the range of 77–98%.
Simultaneous determination of phosphonate, phosphate, and diphosphate by capillary electrophoresis using in‐capillary complexation with Mo(VI)
Authors: Himeno Sadayuki , Inazuma Naoko , Kitano Eri
Published: March 2007

This study describes the simultaneous determination of phosphonate, phosphate, and diphosphate by CE with direct UV detection, based on in‐capillary complexation with Mo(VI). When a mixture of phosphonate, phosphate, and diphosphate was injected into a capillary containing 3.0 mM Mo(VI), 0.05 M malonate buffer (pH 3.0) and 45% v/v CH3CN, three well‐defined peaks, due to the migration of the corresponding polyoxomolybdate anions, were separated. The respective calibration graphs were linear in the concentration range of 2×10–6–2×10–4 M for phosphonate, 1×10–6–5×10–5 M for phosphate, and 1×10–6–2×10–4 M for diphosphate; the correlation coefficients were better than 0.9990. The present CE method is successfully applied to the simultaneous determination of phosphonate, phosphate, and diphosphate in tap water.
Photodynamic therapy for Photogem® and Photofrin® using different light wavelengths in 375 human melanoma cells
Authors: Menezes P F C , Bagnato V S , Johnke R M , Bonnerup C , Sibata C H , Allison R R , Perussi J R
Published: March 2007

Melanoma is the most lethal of all cutaneous malignancies and additional treatment paradigms are needed. We explored the activity of PDT on human A-375 melanoma cells in vitro with different light wavelengths using porphyrin photosensitizers. The effect of red, green, and blue light in the cytotoxicity of these cells was measured, and the results suggest that there are no differences in the photodynamic activity of Photofrin® and Photogem® when irradiated with the blue, green and red light, if the effect of the molar absorption coefficient and the effect of light penetration in the tissue are taking into account. We report the ID10 (irradiation dose responsible for killing 90% of cells) for Photofrin® and Photogem® irradiated in the three wavelengths. The fact that melanoma cells have problems with the absorption of the light due to poor penetration of the light administrated in PDT (red light: 630 nm) suggests that the melanoma cells can be irradiated with blue and green light producing the same cytotoxic result, only with an adjustment of the light dose. This may offer a means to improve clinical PDT for patients with this diagnosis.
Morphological and Thermal Properties of ABS/Montmorillonite Nanocomposites Using ABS with Different AN Contents
Authors: Patiño‐Soto Alma Patricia , Sánchez‐Valdes Saúl , Ramos‐deValle Luis Francisco
Published: March 2007

Acrylonitrile‐butadiene‐styrene (ABS)/clay nanocomposites have been prepared using two types of ABS with different AN contents and a chemically modified clay, Cloisite 20A. The composites were prepared by melt mixing in a twin‐screw extruder. Their morphological properties were characterized by XRD and TEM. The thermal stability of the polymer nanocomposites was studied using TGA and flammability tests. The results were analyzed in terms of the effect of the clay content and the type of ABS used on the clay dispersion and the thermal stability of the nanocomposites. Experimental results confirmed that better dispersion and intercalation and/or exfoliation can be obtained when using an ABS with a higher AN content. The study using TGA and flammability tests showed that the nanodispersed layers of silicate enhanced the thermal stability of the ABS matrix, and that an ABS with higher AN content was more effective in providing fire retardancy. This suggests that when using higher AN contents, more polar groups are present within the polymer matrix, allowing a more homogeneous dispersion and intercalation of the chain polymers into the organomodified montmorillonite clay (MMT), and even some exfoliation of the nanoclay.

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Properties and Dispersion of EPDM/Modified‐Organoclay Nanocomposites
Authors: Kang Donghee , Kim Dongsik , Yoon Sung‐Hwan , Kim Dongkyu , Barry Carol , Mead Joey
Published: March 2007

Elastomers show improved properties when reinforced with nanoclay at low filler loadings, but dispersion of the clay is difficult in non‐polar polymers, such as ethylene propylene diene monomer (EPDM). In this work several compatibilization approaches were studied, including the addition of EPDM modified with maleic anhydride (EPDM‐g‐MA) and the use of organoclay modified with maleic anhydride‐grafted liquid vinyl polybutadiene (LVPB‐g‐MA). The use of LVPB‐g‐MA‐modified organoclay increased the degree of dispersion as measured by X‐ray diffraction, giving increased thermal stability and modulus, and decreased swelling. Flame resistance was poorer for the EPDM/LVPB‐g‐MA‐modified organoclay system compared to the unmodified EPDM/organoclay compound. The resistivity of the nanoclay‐filled composites was lower than the reference EPDM compound, but dielectric properties for the LVPB‐g‐MA modified organoclay were similar to the reference.

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Recyclability of In Situ Microfibrillar Poly(ethylene terephthalate)/High‐Density Polyethylene Blends
Authors: Jiang Chun‐Hua , Zhong Gan‐Ji , Li Zhong‐Ming
Published: March 2007

Repetitive processing was employed to assess the recyclability of in situ microfibrillar poly(ethylene terephthalate) (PET)/high‐density polyethylene (HDPE) blends which were fabricated through a “rectangular slit die extrusion–hot stretching–quenching” process. For comparison, the conventional PET/HDPE blends were also obtained using the same processing operation but without hot stretching. The morphological observation indicated that slit die extrusion and hot stretching successfully made the dispersed PET phase deform in situ into well‐defined microfibrils. The average diameter of the microfibrils increased with the processing cycles. The rheological properties obtained from the parallel‐plate dynamic rheometer suggested that the microfibrillar blends have higher viscosity and viscoelastic moduli (storage and loss moduli) as well as better flow stability than the conventional PET/HDPE blend. More importantly, with the increase in the processing cycles, an increase in yield strength and unchanged tensile modulus were observed for in situ microfibrillar blends, while a decrease in these properties for conventional blend, indicating that the in situ microfibrillar PET/HDPE blends have promising recycling potential.

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Modifying Thermal Expansion of Polymer Composites by Blending with a Negative Thermal Expansion Material
Authors: Chandra Amreesh , Meyer Wolfgang H. , Best Andreas , Hanewald Andreas , Wegner Gerhard
Published: March 2007

Large positive thermal expansion in polymers is one of the major drawbacks in using polymers in applications where the sample dimensions play an important role. In this paper, we report a method to vary the thermal expansion of PMMA‐based polymer composites by blending with a negative thermal expansion material, PbTiO3. It is shown that the thermal expansion coefficient of the composite can be tailored by suitably adjusting the ratio of polymer and ceramic filler. The coefficient of thermal expansion has been measured using temperature‐dependent step‐height measurements via confocal microscopy. Using SEM, it is shown that the ceramic particles are homogeneously dispersed in the polymer matrix if the composite is obtained by the polymerization of the suspension of PbTiO3 in the monomer MMA. Composite formation is confirmed using XRD and Raman spectroscopy. To estimate the technological viability of such composite films, preliminary results of stress‐strain measurements are also presented.

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Cover Picture: Macromol. Mater. Eng. 3/2007
Authors: Moszner Norbert , Salz Ulrich
Published: March 2007

Cover: The pictures on the cover show the clinical follow up of a replacement of an amalgam restoration (A) by an adhesively placed tooth shaded composite filling. For this purpose, the surface of the cavity is etched and primed using a modern self‐etching enamel‐dentin adhesive (B). After filling the cavity with the composite and curing, a high esthetic tooth shaded composite restoration is created (C). Further details can be found in the article by N. Moszner* and U. Salz on page 245.
Triflic‐Acid‐Mediated Polycondensation of Carbonyl Compounds with Aromatic Hydrocarbons – A Theoretical Study
Authors: Lira Alfredo López , Zolotukhin Mikhail G. , Fomina Lioudmila , Fomine Sergei
Published: March 2007

Mono‐ and diprotonated reaction intermediates involved in the acid‐catalyzed polyhydroxyalkylation of aldehydes and ketones of the general formula R1COR2, (R1 = H, CH3, CF3 and R2 = Ph, CH3, CF3) with benzene and biphenyl, were studied theoretically at PBE0/aug‐cc‐PVTZ//PBE0/6‐31 + G** level of theory. The calculations performed for sulfuric acid and TFSA‐catalyzed reactions showed that for all studied reactions the enhancement of the reactivity of diprotonated species is not sufficient to compensate for the large positive Gibbs energy of second protonation. An alternative mechanism has been proposed for the reaction between benzene and benzaldehyde in TFSA involving only monoprotonated species. The low reactivity of carbonyl compounds with electron donating substituents is due to excessive stabilization of monoprotonated species rendering the reaction thermodynamically impossible.

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Periodic solutions of neutral differential models with state‐dependent delay and feedback control
Authors: Yang Zhihui
Published: March 2007

In this paper, the author employs and develops the continuation theory and degree theory for k‐set contractions to investigate the existence of positive periodic solutions of a general neutral functional system with feedback control state‐dependent and distributed delays. The results give new methods for studying neutral systems, which extend and improve existing results, and have further applications in many fields such as population dynamics. Copyright © 2007 John Wiley & Sons, Ltd.
Global existence and exponential stability of periodic solutions for recurrent neural networks with functional delay
Authors: Yang Zhihui
Published: March 2007

This paper proposes a class of more general model of recurrent neural networks with functional delay, which has been found more suitable to apply directly. Simple and easily checkable conditions of existence, uniqueness, and global exponential stability of periodic solution for the recurrent neural network equations are obtained, utilizing the Lyapunov functional method and the theory of coincidence degree. Some known results are generalized and improved. Copyright © 2007 John Wiley & Sons, Ltd.
Investigation of pathways of advanced glycation end‐products accumulation in macrophages
Authors: Nagai Ryoji , Fujiwara Yukio , Mera Katsumi , Otagiri Masaki
Published: March 2007

Advanced glycation end‐products (AGE) play a role in the pathogenesis of several diseases, including diabetic complications and atherosclerosis. In atherosclerotic lesions of human aortas, AGE are localized in the extracellular matrix and intracellularly in foam cells. Two interpretations are possible for AGE accumulation inside macrophages, one is endocytic uptake of extracellular AGE‐proteins by scavenger receptors; the other is intracellular AGE formation inside the macrophages. In the present study, we determined the pathways involved in AGE accumulation inside macrophages. RAW 264.7 cells, a murine macrophage cell line, incubated with BSA and 1600 mM glucose for 40 weeks, recognized heavily modified AGE‐ BSA. In contrast, the cells showed no ligand activity for mildly modified AGE‐BSA, prepared by incubating BSA with 50 mM glucose for 24 weeks. Nε‐(carboxymethyl)lysine (CML)‐modified proteins of about 65 kDa were detected in human monocyte‐derived macrophages incubated for 7 days with 30 mM glucose and phorbol myristate acetate. Furthermore, CML was generated when glycated protein was incubated with hypochloric acid. Taken together, our results indicate that AGE detected inside foam cells in atherosclerotic lesions are generated intracellularly rather than representing endocytic uptake of extracellular AGE‐proteins by scavenger receptors.
Gain estimation by convergence of active element pattern for E‐plane notch phased array antenna
Authors: Kim Junyeon , So Joonho , Jang Won , Cheon Changyul
Published: March 2007

The beam steering gain of E‐plane notch phased array antenna is estimated using the converged active element pattern (AEP) and the directivity of an isotropic linear array. To get the gain for all scan angles, the authors first investigated the convergence of an AEP with the number of finite notch array at the center element. And then, the beam steering gain can be calculated from multiplying the converged AEP by the directivity of an isotropic linear array. To show the usability of this proposed method, a 10‐element E‐plane notch array antenna has been designed and fabricated. The measured AEP of E‐plane notch antenna has a good agreement with the converged AEP. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1047–1049, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22330
Guided modes characteristics in a fiber with left‐handed material
Authors: Shen LuFa , Wang ZiHua
Published: March 2007

A fiber with left‐handed material as the core, and right‐handed material as the cladding has been analyzed by using Maxwell's equations. A Helmholtz equation is obtained and solved. Thus, some characteristic equations are obtained and studied further. Some novel propagation characteristics in LHM fiber are obtained. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1039–1041, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22335
New micromachined interdigital coplanar waveguide
Authors: Sun Xiaofeng , Ding Guifu , Gu Donghua , Li Binhong , Shen Minyi
Published: March 2007

A novel interdigital coplanar waveguide (CPW) has been designed and fabricated and its characteristics have been studied as a function of transmission line parameters. In this interdigital CPW, the ground conductors are thickened by micromachining techniques, which are helpful for reducing the interference between the adjacent parallel sections of center conductor. Within the frequency range from 5 to 20 GHz, the return loss of this structure has two minimal values whose positions change with the structural parameters. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1007–1010, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22336
Broadband circularly polarized wide‐slot antenna
Authors: Xu R. P. , Huang X. D. , Cheng C. H.
Published: March 2007

A new broadband single‐fed circularly polarized (CP) wide‐slot antenna is presented in the letter. The antenna is composed of a wide‐slot, with a T‐shaped stub and a microstrip T‐junction. The CP operation is realized by the interaction from the T‐shaped stub on the wide‐slot and the T‐junction. The antenna has been investigated numerically and experimentally. Measured result shows that the antenna has an impedance bandwidth of 58% and a 3‐dB bandwidth of axial ratio of 22.2%. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1005–1007, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22337
Novel microstrip, rectangular ferrite, circulator
Authors: Adams Ryan S. , Young Jeffrey L. , O'Neil Benton
Published: March 2007

This letter presents a microstrip circulator topology with a rectangular ferrite region. Optimized networks are designed to maximize transducer power gain and to satisfy the perfect circulation condition with a 50 Ohm termination. The design is validated with measured data showing that 20% bandwidth centered at 10 GHz with a 14 dB isolation specification is achievable. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1036–1039, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22338
Comparison between HIE‐FDTD method and ADI‐FDTD method
Authors: Chen Juan , Wang Jianguo
Published: March 2007

This letter gives the comparison of the 3D hybrid implicit–explicit finite‐difference time‐domain (HIE‐FDTD) method with the ADI‐FDTD method through numerical examples. It shows that the HIE‐FDTD method has higher accuracy than the ADI‐FDTD method, especially for larger rate of field variation; the time step size, which has a detrimental effect on the accuracy of ADI‐FDTD, does not affect the accuracy of HIE‐FDTD method. The computation efficiency of the HIE‐FDTD method is higher than ADI‐FDTD method. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1001–1005, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22340
Integrated low‐profile dual loop‐dipole antennas using an embedded electromagnetic bandgap structure
Authors: Kim Jaehoon , Rahmat‐Samii Yahya
Published: March 2007

Electrical characteristics of an electromagnetic bandgap (EBG) structure embedded in a high dielectric layer are studied using FDTD simulation methods. A low‐profile loop antenna is designed above the embedded EBG structure. For diversity applications in wireless communications and biotelemetry, a printed dipole antenna is also incorporated with the low‐profile loop antenna. The experimental results of the antennas are compared with the simulated results, to show how applicable embedded EBG structures are for low‐profile antenna designs. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1085–1089, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22342
The design of a novel waveguide monopulse feeder for linear phased array antenna
Authors: Kim Chan Hong , Lee Yong Hee , Myung Noh Hoon
Published: March 2007

This paper presents a novel type of waveguide monopulse feeder, which has the concept of a space feed, suitable for liner phased array antenna. The design methods and measurement results of the 2‐to‐39 port feeder at X‐band are described. Measurement results show that this feeder has characteristics of the required optimum 1‐D monopulse power distribution, low insertion loss and good input match. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1106–1109, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22347
Enhanced wideband and compact size fractal Kokh antenna
Authors: Mirzapour Babak , Neyestanak Abbas Ali Lotfi
Published: March 2007

A novel wideband and compact size fractal Kokh antenna is described in this article. The return‐loss, E‐plane and H‐plane radiation pattern of the proposed antenna are measured and simulated by Finite Element method. Both experimental and numerical results show that the proposed antenna has smaller size and wideband behavior respect to similar fractal Kokh antenna designs. The Proposed antenna is able to achieve an impedance bandwidth of 19% for VSWR less than 2. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1077–1080, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22349
Ultra‐wideband bandpass filter with a compact two‐layered structure
Authors: Qu Xinan , Zhong Shun‐Shi , Liu Jie
Published: March 2007

A novel ultra‐wideband (UWB) bandpass filter with a compact size is proposed. By using a two‐layered substrate configuration and an H‐shaped slot on the ground, a vertical‐coupled microstrip resonator structure is formed. Three resonant peaks of the proposed structure are extracted around the lower end, the center, and the upper end of the UWB passband. The compact two‐layered filter has an overall length of about a half guided wavelength at the center UWB frequency and exhibits promising performance for UWB applications. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49:1049–1051, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22351
Multitap coherence‐free photonic RF filter employing semiconductor optical amplifier
Authors: Zheng Rong , Alameh Kamal , Lee Yong Tak , Wang Zhenglin
Published: March 2007

A novel multitap coherence‐free photonic bandpass RF filter utilizing the cross‐gain modulation property of the semiconductor optical amplifier to convert a coherent RF‐modulated laser carrier to a low‐coherence light that is sliced and delayed to realize a stable transversal RF filter. An 8‐tap photonic RF bandpass filter operating at 2.25 GHz with more than 15 dB rejection is experimentally demonstrated. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1103–1106, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22352
Meandering probe fed patch antenna with high gain characteristic for circularly polarized application
Authors: Lai Hau‐Wah , Luk Kwai‐Man
Published: March 2007

A meandering probe‐fed circularly polarized stacked patch antenna with truncated corners is studied. The antenna has a wide 3‐dB axial ratio bandwidth of 12%. It exhibits a stable radiation pattern across the axial ratio bandwidth. The antenna has low cross polarization and high gain, which are −14 dB and 10 dBi, respectively. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1095–1098, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22357
Ultraflat supercontinuum generation in a dispersion‐flattened microstructure fiber
Authors: Zhang Xia , Ren Xiaomin , Xu Yongzhao , Wang Zinan , Huang Yongqing
Published: March 2007

We demonstrate the generation of an ultraflat supercontinuum from an 80‐m long dispersion‐flattened microstructure fiber when coupling a 1.6‐ps pump pulse at a wavelength of 1550 nm. Over 1000 channels of 10‐GHz spacing are generated in a bandwidth of 80 nm, with a flatness of ±1.5 dB in the 1550‐nm band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49:1062–1064, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22362
A novel substitute design for low pass strip line filter
Authors: Bu Shirong , Luo Zhengxiang , Yang Kai , Liu Juanxiu , Ning Junsong
Published: March 2007

A low pass strip line filter is fabricated by microstrip line design. This substitute method is validated by simulated and tested results. This method can be used in the design of TEM planar passive circuits. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1175–1178, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22365
Accurate computation of wide‐band response of electromganetic scattering problems via Maehly approximation
Authors: Chen Mingsheng , Wu Xianliang , Huang Zhixiang , Sha Wei
Published: March 2007

The best uniform rational approximation, performed by the Maehly approximation, is applied to the method of moments (MOM) to obtain the radar cross section (RCS) over a broad frequency band. Numerical results for three dimensional arbitrarily shaped perfectly electrically conducting (PEC) bodies are considered. Compared with the asymptotic waveform evaluation (AWE) technique, the presented technique is found to be efficient in much broader frequency band with lower memory required. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1144–1146, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22367
A high‐frequency and high‐power quasi‐class‐E amplifier design using a finite bias feed inductor
Authors: Van Ju‐Ho , Kim Min‐Su , Jung Sung‐Chan , Park Hyun‐Chul , Ahn Gunhyun , Park Cheon‐Seok , Kim Byung‐Sung , Yang Youngoo
Published: March 2007

This paper presents a design method for a compact high‐efficiency quasi‐class‐E amplifier, using a finite bias feed inductor. It is very difficult to achieve proper class‐E operation from high‐power transistors operating in the high‐frequency region because of their internal parasitic components. To mitigate the effects of internal parasitic components on class‐E operation, a finite DC feed inductance is introduced to resonate out the capacitive parasitic components. A quasi‐class‐E amplifier with a finite DC feed inductor was designed and implemented at 1.2 GHz using a high‐power laterally diffused metal‐oxide‐semiconductor field‐effect transistor (LDMOSFET). We compared simulated time domain current and voltage waveforms with ideal ones. As the test results indicated, power‐added efficiency as high as 70.4% was achieved, at high output power of 39.55 dBm, without losing the circuits' simplicity, one of the most important advantages of class‐E operation. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1114–1118, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22368
RF stationary waves integrated Fourier transform spectrometer
Authors: Hemour S. , Podevin F. , Rauly D. , Xavier P.
Published: March 2007

We describe here a new type of analog correlators based on stationary waves recovery and spatial Fourier transformation. The theoretical basis of the stationary waves integrated Fourier transform spectrometer (SWIFTS) is first introduced. Based on robust physical principles validated by circuits type simulations, the spectrometer could be an interesting competitor to actual RF analog correlators. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1138–1142, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22375
Gain enhancement of a dielectric resonator antenna with use of surface mounted short horn
Authors: Nasimuddin  , Esselle Karu P.
Published: March 2007

We demonstrate the gain of a standard rectangular dielectric resonator antenna (DRA) enhanced by integrating it with a surface mounted short horn (SMSH). An enhancement of gain by 3.8 dB to 8.5 dBi at 5.95 GHz, and a 10 dB return bandwidth of 3.2% has been achieved from this configuration. Total height of the fabricated structure is only 0.172 λ0, or 8.61 mm at 6.0 GHz, and the aperture size is 0.96 λ0 × 0.86 λ0, or 48.1 mm × 43.1 mm. The cross‐polarization level of the antenna is <33 dB in both E‐ and H‐planes. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1162–1166, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22379
Dual‐band monopole antenna excited by a capacitive coupling feed for WLAN applications
Authors: Huang Chih‐Yu , Lin Hsiao‐Cheng , Kuo Jieh‐Sen
Published: March 2007

A printed dual‐band T‐shaped monopole antenna with a shorted strip fed by a coupling microstrip line for wireless communication in the wireless local‐area network (WLAN) band is studied. The proposed antenna can provide two separate impedance bandwidths of 101 MHz (about 4.1% centered at 2.45 GHz) and 1490 MHz (about 27% centered at 5.5 GHz), making it easier to cover the required bandwidths for WLAN operation in the 2.45 GHz band (about 3.4% bandwidth required) and 5.2/5.8 GHz bands (about 13% bandwidth required). We can easily find the enhancement of impedance bandwidth by using capacitive coupling feed. Details of the proposed antenna design and experimental results are presented and discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1135–1138, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22380
Ultra‐wideband planar shorted dipole antenna with two C‐shaped arms for wireless communications
Authors: Li Wei‐Yu , Wong Kin‐Lu , Su Saou‐Wen
Published: March 2007

A novel ultra‐wideband (UWB) planar shorted dipole antenna capable of generating a 9:1 bandwidth (820–7340 MHz) covering the present‐day mobile communication systems (AMPS, GSM, DCS, PCS, UMTS) and WLAN systems in the 2.4/5.2/5.8 GHz bands is presented. The proposed planar antenna is easily fabricated from a metal plate and is generally in the form of the dipole antenna with two C‐shaped radiating arms short‐circuited to each other through two shorting strips. By selecting a proper length of the shorting strips, the proposed antenna can have the lower edge frequency of its operating band reduced to be as low as 820 MHz, with a compact size of 109 × 170 mm2. The proposed antenna is studied in detail in the article. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1132–1135, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22381
Ka‐band 0.18 μm CMOS low noise amplifier with 5.2 dB noise figure
Authors: Chang Win‐Ming , Hsiung Zi‐Hao , Jou Christina F.
Published: March 2007

A Ka‐band low noise amplifier (LNA) using three cascaded stages was designed and implemented in a standard 0.18 μm CMOS technology. The fabricated Ka‐band LNA achieves power gain (S21) above 12 dB from 30 to 32 GHz and a minimal noise figure of 5.2 dB at 31.5 GHz. The three cascaded stages LNA consume 15.58 mA from 1 V power supply. Compared with the recent published literatures, this LNA operates at the highest frequency ever reported by standard bulk 0.18 μm CMOS process. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1187–1189, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22383
A low phase noise design for ultrawideband frequency synthesizer
Authors: Chang Po‐Yang , Wu Hui‐I , Jou Christina F.
Published: March 2007

A low phase‐noise frequency synthesizer design for ultrawideband is demonstrated in a 0.18‐μm CMOS process. It combines a low phase‐noise voltage‐controlled oscillator with two‐stage dividers and a switched buffer multiplexer with low layout complexity. Because of the symmetrical independent architecture of this switch buffer design, it can reduce the additional phase noise created by the traditional multiplexer stage. Here, this low phase noise design in three LO bands (8448, 4224, and 2112 MHz) is demonstrated. The measurement shows that in these three LO band, this new structure can achieve phase noise of less than −121 dBc/Hz at 1 MHz offset. The frequency tuning range is 10% while consuming only 52.2 mW from a 1.8‐V supply. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1159–1162, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22384
Novel design of a dual‐frequency and a multi‐frequency microstrip antenna
Authors: Huang Zhenhua , Zhou Xilang , Niu Jiaxiao , Chen Junhua
Published: March 2007

A novel H‐shaped dual‐frequency microstrip antenna has been investigated. This novel microstrip antenna is considered to be composed of two microstrip dipoles, which resonate at the antenna's two operating frequencies, respectively. The resonant frequencies are predicted. Return loss, radiation patterns of the antenna have been investigated numerically and experimentally, and good agreement is achieved. Furthermore, the size of the antenna is more compact than conventional H‐shaped antennas. Then a modified H‐shaped multi‐frequency microstrip antenna is proposed. Simulation and experimental results are also presented and discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1129–1131, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22386
Characteristic of the ultra‐wideband electromagnetic radiation generated by PCSS
Authors: Ruan Chi , Zhao Wei , Chen Guo‐Fu , Zhu Shao‐Lan
Published: March 2007

A novel ultra‐wideband electromagnetic pulse generating method based on the photoconductive semiconductor switches (PCSS) is presented. Gallium arsenide is used to develop the PCSS for an ultrashort electromagnetic pulse source. The pulse generated by such PCSS is within picosecond (ps) time scale, and can yield power pulse with an voltage over 10 kV. The experimental results show that the pulses are stable, with the peak–peak amplitude change of 6% and the time jitter within several picoseconds. The radiations of the PCSS triggered by the picosecond laser and femtosecond laser pulse series illustrate that the electromagnetic pulses would have high repetition of more than 80 MHz and frequency bandwidth of DC‐6 GHz. The radiations of “lock‐on” mode of the PCSS are also analyzed here. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1118–1122, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22393
Improved high rejection for notch filter using square ring resonator with flexible electromagnetic coupling
Authors: Harikrishna J. V. S. , Karekar R. N. , Aiyer R. C.
Published: March 2007

A novel technique of electromagnetic coupling for microstrip notch filter is reported, It employs a full wave (λg) square ring microstrip resonator for 2.4 GHz with one arm (λg/4) coupled electromagnetically to a 2‐port 50‐Ω feed line, under it. The square ring resonator and feed line are on two separate TMM4 (εr = 4.5) substrates. Electromagnetic coupling not only offers improved rejection but also the flexibility in various ways, for example, for easy replacement of resonator. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1201–1203, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.22396
60‐GHz transceiver module with coplanar ribbon bonded planar millimeter wave bandpass filter
Authors: Choi Sung Tae , Yang Ki Seok , Tokuda Kiyohito , Kim Yong Hoon
Published: March 2007

A small size 60‐GHz full duplex transceiver module is developed for high data rate millimeter wave wireless access link. To realize a compact and low cost transceiver module, a planar millimeter wave bandpass filter is integrated by using broadband coplanar ribbon‐bond interconnects in the module. The overall size of the module except input and output connectors is 50 mm × 75 mm × 23 mm. The measured RF output power is 16 dBm at 1‐dB compression, with conversion gain of 30.6 dB and the conversion gain of the receiver being 23.4 dB. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1212–1214, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.22399
Erratum: Integral equation‐based overlapped domain decomposition method for the analysis of electromagnetic scattering of 3D conducting objects
Authors: Li Wei‐Dong , Hong Wei , Zhou Hou‐Xing
Published: March 2007

Originally published Microwave Opt Technol Lett 49: 265–274, 2007. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1225–1230, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22479