bluuebunny/crossref_metadata_2025 huggingface dataset:
Levitation force assist through LSM armature currents in superconducting maglev vehicle
Authors: Sakamoto Tetsuzo , Kobayashi Toshihiro
Published: April 2006

In a superconducting maglev vehicle, levitation forces produced by the interaction between the ground levitation coils and the onboard SCMs become insufficient when the running speed is low. This paper presents a levitation force assist method through the control of LSM armature currents, which usually function to generate propulsion forces. The levitation assist system is constructed in terms of d‐axis armature currents, leading to the definition of the vertical force coefficient of propulsion system. The calculated results show the feasibility of the system, which produces damping forces as well as levitation assist forces. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(4): 45–52, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20260
Application study of a high‐temperature superconducting fault current limiter for electric power system
Authors: Shimizu Iwao , Naito Yuji , Yamaguchi Iwao , Kaiho Katsuyuki , Yanabu Satoru
Published: April 2006

Using high‐temperature superconductors, a superconducting fault current limiter (SFCL) was fabricated and tested. The superconductor and a vacuum interrupter serving as a commutation switch were connected in parallel with a bypass coil. When a fault occurs and excessive current flows, the superconductor is first quenched and the current is transferred to the bypass coil because of the voltage drop of the superconductor. At the same time, since a magnetic field is generated by the current flowing in the bypass coil, the commutation switch is immediately driven by an electromagnetic repulsion plate connected to the driving rod of the vacuum interrupter (VI), and the superconductor is separated from this circuit. Using the test model, we were able to separate the superconductor from the circuit by the movement of the VI within a half current cycle and to transfer all current to the bypass coil. Since the operation of the commutation switch is included in the current limiting operation of this test model, it will be a useful circuit in the development of SFCL in the future. Moreover, since it can make the energy consumption of the superconductor small during the fault state due to the realization of a high‐speed switch with simple composition, the burden on the superconductor is reduced compared with the conventional resistive type of SFCL and it is considered that the flexibility of SFCL design is increased. Cooperation with a circuit breaker was also considered; trial calculations of the parameters and energy of operation were conducted and a discussion of the installation of the SFCL in an electric power system is presented. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(4): 20–29, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20265
Study on method to detect loss of synchronism using bus voltage and line current measured on a line using power system simulator
Authors: Takaoka Masaomi , Kiuchi Toru , Sato Masahiro
Published: April 2006

A severe fault may cause loss of synchronism of a small number of generators. And it may take many generators out of service resulting in a wide area blackout. When two groups of generators lose synchronism, the magnitude of voltage on some lines becomes zero. Therefore, an approach whereby lines with zero voltage are opened has been employed in order to prevent loss of synchronism from extension. This paper presents a new method using voltage and current measured on a line during disturbance to detect the line with zero voltage at the instant when loss of synchronism takes place. A method to detect loss of synchronism using voltage and current measured on a line was already proposed. This paper presents results of the tests performed using a power system simulator which is composed of a DC motor, a synchronous generator, artificial transmission line, circuit breaker equipment, and so on. The validity of the proposed methods was verified by finding loss of synchronism correctly. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(4): 7–19, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20346
Observations of seismic electromagnetic phenomena in VHF band by dual frequency method
Authors: Yoshida Teruaki , Nishi Masahiro , Mochizuki Keisuke
Published: April 2006

Seismic electromagnetic (EM) phenomena have been observed at many laboratories with specially designed systems. Recently we can utilize radio receivers, personal computers, and communication systems with higher performances and reasonable cost. It is possible to observe seismic EM phenomena not only by specially designed systems but also by a simple observation system integrated by these devices and systems. We have created an observation system for seismic EM phenomena with them in the very high frequency (VHF) band, from 76 MHz to 90 MHz, assigned for FM broadcasting exclusive use in Japan. We are surrounded by many EM waves, such as broadcasting, communication usage, and man‐made noises. Thus, we have newly developed the dual frequency observation method. In this paper, we describe an observation method that can identify whether a received signal is a broadband EM wave or an artificial FM radio wave. Next, the observation results for broadband EM waves from galactic noise and solar flares are presented. Then, the observation results for FM radio waves reflected from sporadic E layer and the Leonid meteors are shown. Finally, the observation results for the detected broadband EM waves associated with the Geiyo earthquake are described. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(4): 36–44, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20350
Attempted biofiltration of reduced sulphur compounds from a pulp and paper mill in Northern Sweden
Authors: Chan Anneli Andersson
Published: April 2006

The objective of this study was to identify the reduced sulphur compounds (RSCs) present in waste gas from a specific deaerator at a pulp and paper mill in northern Sweden, and to investigate the feasibility of a multi‐stage biofilter to treat these compounds in an industrial setting. Two filter media, rockwool mats and an organic peat and compost mixture, were used as biofilter media. A mixed population of heterotrophs and a strain of Hypomicrobium were examined for DMS and DMDS degradation. Two experimental periods were performed for 45 days each, in the fall and winter in cold climate. Process parameters as well as the number of viable cells of the filter were monitored during operation. Results were inconsistent due to the fluctuations of the system, and a number of operational problems were identified, differing from those developed under controlled, laboratory set‐ups. Process conditions varied greatly, that is, fluctuating temperatures, pollutant concentrations, and airflows that led to insufficient residence times. Both biological and mass transfer limitations are possible explanations for the poor treatment results. This study can contribute to assessing the feasibility of biofilters in the pulp and paper industry, and help reduce the knowledge gap between laboratory studies and field conditions. © 2006 American Institute of Chemical Engineers Environ Prog, 2006
Stratigraphic investigations at Los Buchillones, a coastal Taino site in north‐central Cuba
Authors: Peros Matthew C. , Graham Elizabeth , Davis Anthony M.
Published: April 2006

The authors present stratigraphic data from Los Buchillones, a now submerged Taino village on the north coast of central Cuba that was occupied from some time prior to A.D. 1220 until 1640 or later. Los Buchillones is one of the best‐preserved sites in the Caribbean, with material culture remains that include palm thatch and wooden structural elements from some of the more than 40 collapsed structures. The purpose of this study was to investigate the environment and site‐formation processes of the Taino settlement. Sediment cores were sampled from the site and its vicinity to permit integration of the geological and archaeological stratigraphies. The cores were analyzed for color, texture, mollusk content, elemental geochemistry, and mineralogy. The results of the stratigraphic work are consistent with regional sealevel data that shows relative sea level has risen gradually during the late Holocene, but has remained relatively stable since the time the Taino first occupied Los Buchillones. Of the two structures partially cleared, at least one appears to have been built over the water, supported on pilings. Site selection is likely to have resulted from a consideration of environmental factors, such as access to marine, terrestrial, and lagoonal resources, and proximity to freshwater springs. © 2006 Wiley Periodicals, Inc.
Sediment consolidation and archaeological site formation
Authors: Andrews Brian N.
Published: April 2006

Consolidation is the reduction in sediment volume that occurs in response to natural overburden loading. As void space is reduced, solid particles within the consolidating sediment undergo rearrangement, including downward displacement and reduction in inclination angle. Buried artifacts are also subject to this rearrangement. An experiment was designed to simulate consolidation of artifact‐bearing sediments and document the extent of artifact rearrangement caused by varying degrees of consolidation. Results indicate that artifacts will generally follow the downward movement of the sediment regardless of individual artifact attributes, and that significant reductions in artifact inclination angle can occur. © 2006 Wiley Periodicals, Inc.
Petrography and provenance of Laecanius Amphorae from Istria, northern Adriatic region, Croatia
Authors: Mange Maria A. , Bezeczky Tam´s
Published: April 2006

Amphorae sherds from the Laecanius workshop of Roman Istria (10–5 B.C. and 78 A.D.), Croatia, were studied by integrating archaeological and geological techniques including fabric analysis, thin‐section petrography, X‐ray diffractometry (XRD), and heavy mineral analysis. The fabric of the sherds showed distinctive characteristics, permitting their classification and allocation into nine fabric groupss. Petrography revealed that quartz is the dominant clastic component, whereas carbonate is common as temper; XRD provided information on firing temperatures that ranged between 750 and 900°C. The sherds contain diverse heavy mineral suites with generally high epidote and garnet proportions; zircon is occasionally important. Garnet/epidote ratios and the presence of diagnostic species (pyroxene, hornblende) showed systematic variations that coincided with similar variations in fabric characteristics. Heavy mineral signatures of amphorae produced in other workshops proved essential in differentiating them from Laecanius sherds. A comparative heavy mineral analysis of terra rossa samples from the vicinity of the workshop indicated that terra rossa was the major source for the paste. Differences observed in the heavy mineral composition of the sherds and terra rossa were interpreted by the spatial heterogeneity of the latter and the mixing of the paste with sandy temper. Fresh Adriatic sponge spicules in the majority of Laecanius sherds and the temper‐derived, generally immature heavy mineral assemblages suggest that sandy deposits from the Adriatic were used for the clastic temper. © 2006 Wiley Periodicals, Inc.
Coloring and preservation state of faunal remains from the neanderthal levels of Kůlna Cave, Czech republic
Authors: Michel Véronique , Bocherens Hervé , Théry‐Parisot Isabelle , Valoch Karel , Valensi Patricia
Published: April 2006

The preservation process of faunal remains from the Middle Paleolithic levels of Kůlna Cave was studied within a taphonomic and palaeodietary framework. A visual examination of bones and teeth showed that they display a wide variety of colors. Chemical analyses (C, N, Fe, Mn) and a combination of analytical techniques, such as Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), and electron spin resonance (ESR) spectrometry, were conducted on 13 fossil remains. The crystallinity indexes, IR‐SF, XRD‐CI, XRD‐L200, the IR area band (Amide I), and the ESR analyses showed that the bones were not burned at a temperature higher than 200°C. This implies that the bone remains were not used as fuel by Neanderthals at Kůlna Cave. Coloring in these bones is largely due to the presence of Mn and Fe. © 2006 Wiley Periodicals, Inc.
Short contribution: Buried Canopic channel identified near Egypt's Nile delta coast with radar (SRTM) imagery
Authors: Stanley Jean‐Daniel , Jorstad Thomas F.
Published: April 2006

Shuttle Radar Topography Mission (SRTM) data, with ground‐based geologic investigations, define the geographic position of the relict Canopic channel in Egypt's NW Nile delta. Two sinuous channel segments south of Abu Qir Bay are observed on a radar image: a more sinuous trace (36 km in length) west of Idku lagoon, and an eastern one (˜20 km), reaching the lagoon's southeast corner. Sediment cores recovered along channel traces show sand‐rich deposits (to > 4 m thick) beneath the surface, in contrast with silty muds in areas away from channels. Historic and archaeological findings indicate that the Ptolemaic Roman city of Schedia once lay directly along the Canopic that channeled water from the 3rd to 2nd centuries B.C. until ˜5th century A.D., after which Nile water was displaced to the east via Bolbitic and, later, Rosetta branches. Identification of buried, but well‐defined, Canopic channels provides baselines for renewed archaeological exploration in this delta sector. © 2006 Wiley Periodicals, Inc.
Temporal and spatial variations of canopy temperature over a C3C4 mixture grassland
Authors: Shimoda S. , Oikawa T.
Published: April 2006

This study discusses the photosynthetic pathway types involved in canopy temperature measurements on a mixed grassland consisting of C3 and C4 plants (dominant species in biomass were Solidago altissima (C3), Miscanthus sinensis (C4), and Imperata cylindrica (C4)). In the wet conditions immediately after the rainy season, the mean canopy temperature for S. altissima was the lowest among the dominant species, mainly due to its leaf conductance being twice as large as the other two species. Despite using the same C4 photosynthetic pathway, M. sinensis had a lower apparent canopy temperature than I. cylindrica due to a smaller proportion of sunlit elements in the field of view. In the dry conditions during late July, the mean canopy temperatures of the three dominant species were within 0·3 °C of one another. These results can be explained by poor water conditions for C3 species (S. altissima). The simultaneous survey of vegetation and thermal imaging can help clarify characteristics of C3 and C4 canopy temperature over complicated grassland. Copyright © 2006 John Wiley & Sons, Ltd.
On the use of finite‐difference and neural‐network models to evaluate the impact of underground water overexploitation
Authors: Hani A. , Lallahem S. , Mania J. , Djabri L.
Published: April 2006

The purpose of this study is to include expert knowledge as one part of the modelling system and thereby offer the chance to create a productive interactive system between expert, mathematical model, ASM, and artificial neural networks (ANNs). An attempt to determine outflow‐influencing parameters in order to simulate spring flow is presented. The Bouteldja dune aquifer is fed by rains and streaming water on the sandy argillaceous relieves in the Est. The lateral passage to the gravel of the Bouteldja Plain is marked by numerous bogs that correspond to the piezometric level. These bogs have long been an environment for migratory birds and a natural reserve for many species. However, the continued exploitation of about 30 wells has negatively influenced the hydrodynamic equilibrium of the aquifer and has brought a diminution of the sources' capacity.

In this study, we tried by using a hydrodynamic model and the neural network to ascertain the state of the resources and to identify the factors responsible for the decreasing flows of the three principal springs of the area (Bougles, Bourdim and Titteri) by using neural networks. The results obtained show a continued exhaustion of the reserve since 1986 with a large cone of depression. The ANNs show that the decrease in flows of the springs is not only due to the unfavourable climatic conditions, but also to the intensive exploitation of the aquifer. These results show that the groundwater reserves are decreasing over time, thus highlighting the need to take some urgent measures to stop this phenomenon. Copyright © 2006 John Wiley & Sons, Ltd.
Effect of reinforcement particle size on in vitro behavior of β‐tricalcium phosphate‐reinforced high‐density polyethylene: A novel orthopedic composite
Authors: Homaeigohar S. SH. , Shokrgozar M. A. , Javadpour J. , Khavandi A. , Sadi A. Yari
Published: April 2006

β‐Tricalcium phosphate‐reinforced high‐density polyethylene (β‐TCP/HDPE) is a new biomaterial, which was made to simulate bone composition and study its capacity to act like bony tissues. This material was produced by replacing mineral component and collagen soft tissue of bone with β‐TCP and HDPE, respectively. The biocompatibility of composite samples with different volume fractions of TCP (20, 30, and 40 vol %) and two different particle sizes (80–100 and 120–140 mesh size) was examined in vitro using the osteoblast cell line G‐292 by proliferation, alkaline phosphatase (ALP) production, and cell adhesion assays. Cell–material interaction on the surface of the composites was observed by scanning electron microscopy (SEM). The effect of β‐TCP particle size on behavior of the osteoblast cell line was compared between two groups of the composite samples containing smaller and larger reinforcement particle sizes as well as with those of a negative control. In general, results showed that the composite samples containing larger particles supported a higher rate of proliferation and ALP production by osteoblast cells after 3, 7, and 14 days of incubation compared to the composite samples with smaller particle size and control. Furthermore, more cells were attached to the surface of composite samples containing larger particle size when compared to the smaller particle size composites (p < 0.05). This number was nearly equal with numbers adhered on negative control [tissue culture polystyrene (TPS)] and significantly higher in comparison with composite control [polyethylene (PE)] (p < 0.05). Adhered cells presented a normal morphology by SEM and many of the cells were seen to be undergoing cell division. These findings indicate that β‐TCP/HDPE composites are biocompatible, nontoxic, and in some cases, act to stimulate proliferation of the cells, ALP production, and cell adhesion when compared to the control counterparts. Furthermore, β‐TCP/HDPE samples with larger reinforcement particle size were shown to possess better biological properties. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Copolymerisation of ε‐caprolactone and hydrosilanes to poly(caprolactone‐co‐silane)s using Cp2MCl2/Red‐Al (M = Ti, Zr, Hf) combination catalysts
Authors: Kim Bo‐Hye , Woo Hee‐Gweon , Kim Whangi , Li Hong
Published: April 2006

The non‐reductive ring‐opening/dehydrocoupling copolymerisation of ε‐caprolactone with various primary hydrosilanes (RSiH3: phenylsilane, p‐tolylsilane, benzylsilane, p‐methylbenzylsilane and phenethylsilane) and secondary hydrosilanes (RR′SiH2: phenylmethylsilane and diphenylsilane) using Cp2MCl2/Red‐Al (M = Ti, Zr, Hf) combination catalysts produced random copolymers, poly(caprolactone‐co‐silane)s, in good yield. For all the primary hydrosilanes the polymerisation yield and molecular weight decreased in the order Ti > Zr > Hf whereas the thermogravimetric analysis (TGA) residue yield increased in the order Ti < Zr < Hf. The molecular weights with secondary hydrosilanes were higher than those with primary hydrosilanes, while a reverse trend was observed for TGA residue yield. A plausible mechanism for the formation of the random copolymers is provided. Copyright © 2006 Society of Chemical Industry
Studies on the synergistic extraction of rare earths with a combination of 2‐ethylhexylphosphonic acid mono‐2‐ethylhexyl ester and trialkylphosphine oxide
Authors: Sun Xiaobo , Meng Shulan , Li Deqian
Published: April 2006

The synergistic extraction of rare earths (La, Nd, Gd, Y and Yb) with a mixture of 2‐ethylhexyl 2‐ethylhexylphosphonate (EHEHPA) (HA) and trialkylphosphine oxide (Cyanex 923) (B) from a hydrochloride medium was investigated. The mixed system significantly enhances the extraction efficiency for lighter lanthanides and the synergistic enhancement coefficients for La (4.52), Nd (3.35), Gd (2.08), Y (1.31) and Yb (1.08) decrease with decreasing ionic radius of the rare earths. The extraction equilibrium of La, Nd and Gd indicate that La and Nd were extracted as MA3·B, whereas Gd was extracted as Gd(OH)A2(HA)2·B. The equilibrium constants, thermodynamic functions such as ΔG, ΔH and ΔS and formation constants of the extracted species were determined. The stripping properties were also studied. Copyright © 2006 Society of Chemical Industry
Morphological and structural characteristics of aerobic granulation
Authors: Li Jiuyi , Chen Yong , Li Jin , Zhang Donghua , Wang Shuguang , Wang Lianjun , Jiang Dong , Sun Feiyun , Zhang Qiong
Published: April 2006

The morphological and structural characteristics of aerobic granulation were investigated in a sequencing batch reactor. Small granules consisting mainly of bacterial microcolonies first formed at an organic loading rate of 1.68 kg chemical oxygen demand (COD) m−3 d−1 and a minimal settling velocity of 9.6 m h−1. Mycelial granules consisting of fungi and filamentous microorganisms formed as the minimal settling velocity increased to 18 m h−1. Scanning electronic microscopic observations indicated that fungi formed the structural backbone upon which other microorganisms can attach and colonize. The attached organisms began to reproduce themselves and quickly fill up the spatial voids within the granules. When the organic loading rate of the reactor increased to 4.2 kg COD m−3 d−1, the granules exhibited a denser and more compact structure and bacteria with a variety of morphotypes, embedded in extracellular polymeric substances, dominated. When the aerobic filling time was extended from 5 to 30 min, the thick and compact granules were gradually shifted into a light and loose filamentous granular structure. The extension of the aerobic filling time eventually led to instability and the failure of reactor operation. Copyright © 2006 Society of Chemical Industry
Comparative analysis of neuroectodermal differentiation capacity of human bone marrow stromal cells using various conversion protocols
Authors: Hermann Andreas , Liebau Stefan , Gastl Regina , Fickert Stefan , Habisch Hans‐Jörg , Fiedler Jörg , Schwarz Johannes , Brenner Rolf , Storch Alexander
Published: April 2006

Human adult bone marrow‐derived mesodermal stromal cells (hMSCs) are able to differentiate into multiple mesodermal tissues, including bone and cartilage. There is evidence that these cells are able to break germ layer commitment and differentiate into cells expressing neuroectodermal properties. There is still debate about whether this results from cell fusion, aberrant marker gene expression or real neuroectodermal differentiation. Here we extend our work on neuroectodermal conversion of adult hMSCs in vitro by evaluating various epigenetic conversion protocols using quantitative RT‐PCR and immunocytochemistry. Undifferentiated hMSCs expressed high levels of fibronectin as well as several neuroectodermal genes commonly used to characterize neural cell types, such as nestin, β‐tubulin III, and GFAP, suggesting that hMSCs retain the ability to differentiate into neuroectodermal cell types. Protocols using a direct differentiation of hMSCs into a neural phenotype failed to induce significant changes in morphology and/or expression of markers of early and mature glial/neuronal cells types. In contrast, a multistep protocol with conversion of hMSCs into a neural stem cell‐like population and subsequent terminal differentiation in mature glia and neurons generated relevant morphological changes as well as significant increase of expression levels of marker genes for early and late neural cell types, such as nestin, neurogenin2, MBP, and MAP2ab, accompanied by a loss of their mesenchymal properties. Our data provide an impetus for differentiating hMSCs in vitro into mature neuroectodermal cells. Neuroectodermally converted hMSCs may therefore ultimately help in treating acute and chronic neurodegenerative diseases. Analysis of marker gene expression for characterization of neural cells derived from MSCs has to take into account that several early and late neuroectodermal genes are already expressed in undifferentiated MSCs. © 2006 Wiley‐Liss, Inc.
Long‐lasting coexpression of nestin and glial fibrillary acidic protein in primary cultures of astroglial cells with a major participation of nestin+/GFAP− cells in cell proliferation
Authors: Sergent‐Tanguy Solène , Michel Delphine C. , Neveu Isabelle , Naveilhan Philippe
Published: April 2006

Nestin, a currently used marker of neural stem cells, is transiently coexpressed with glial fibrillary acidic protein (GFAP) during development and is induced in reactive astrocytes following brain injury. Nestin expression has also been found in cultures of astroglial cells, but little is known about the fate and the mitotic activity of nestin‐expressing cells in this in vitro model. The present study reveals a long‐lasting expression of nestin in primary cultures of astroglial cells derived from the rat brain. Over 70% of the cells were nestin+ at 12 weeks, with a large majority coexpressing the GFAP astrocytic marker. Time‐course analyses supported a transition from a nestin+/GFAP− to a nestin+/GFAP+ phenotype over time, which was further increased by cell cycle arrest. Interestingly, double staining with Ki67 revealed that over 90% of cycling cells were nestin+ whereas only 28% were GFAP+ in a population consisting of almost equivalent numbers of nestin+ and GFAP+ cells. These observations indicated that nestin+/GFAP− cells are actively engaged in mitotic activity, even after 2 weeks in vitro. Part of these cells might have retained properties of neural stem cells, insofar as 10% of cells in a primary culture of glial cells were able to generate neurospheres that gave rise to both neurons and astrocytes. Further studies will be necessary to characterize fully the proliferating cells in primary cultures of glial cells, but our present results reveal a major contribution of the nestin+/GFAP− cells to the increase in the number of astrocytes, even though nestin+/GFAP+ cells proliferate also. © 2006 Wiley‐Liss, Inc.
Unconjugated bilirubin activates and damages microglia
Authors: Gordo Ana C. , Falcão Ana S. , Fernandes Adelaide , Brito Maria A. , Silva Rui F.M. , Brites Dora
Published: April 2006

Microglia are the resident immune cells of the brain and are the principal source of cytokines produced during central nervous system inflammation. We have previously shown that increased levels of unconjugated bilirubin (UCB), which can be detrimental to the central nervous system during neonatal life, induce the secretion of inflammatory cytokines and glutamate by astrocytes. Nevertheless, the effect of UCB on microglia has never been investigated. Hence, the main goal of the present study was to evaluate whether UCB leads to microglial activation and to the release of the cytokines tumor necrosis factor (TNF)‐α, interleukin (IL)‐1β, and IL‐6. Additionally, we investigated the effects of UCB on glutamate efflux and cell death. The results showed that UCB induces morphological changes characteristic of activated microglia and the release of high levels of TNF‐α, IL‐1β, and IL‐6 in a concentration‐dependent manner. In addition, UCB triggered extracellular accumulation of glutamate and an increased cell death by apoptosis and necrosis. These results demonstrate, for the first time, that UCB is toxic to microglial cells and point to microglia as an important target of UCB in the central nervous system. Moreover, they suggest that UCB‐induced cytokine production, by mediating cell injury, can further contribute to exacerbate neurototoxicity. Interestingly, microglia cells are much more responsive to UCB than astrocytes. Collectively, these data indicate that microglia may play an important role in the pathogenesis of encephalopathy during severe hyperbilirubinemia. © 2006 Wiley‐Liss, Inc.
A Study of the Photoorientation Phenomena in Cholesteric Polymer Systems Containing Photochromic Diarylethene Derivatives
Authors: Medvedeva Dasha , Bobrovsky Alexey , Boiko Natalia , Shibaev Valery , Shirinyan Valery , Krayushkin Mikhail
Published: April 2006

Summary: Photoorientation processes in two cholesteric mixtures were studied. Mixture I contained a nematogenic phenylbenzoate homopolymer, a photochromic diarylethene dopant and a chiral dopant. Mixture II consisted of a binary comb‐shaped nematogenic copolymer with fluorescent perylene side groups and the same chiral and photochromic dopants. Irradiation of the mixtures with a polarized UV light did not induce photoorientation of the photoinduced “closed” form of the diarylethene dopant. However, the action of a polarized visible light on films of mixtures irradiated with UV light led to the appearance of dichroism. This phenomenon is associated with the photoselection process of the photochromic diarylethene molecules in the cholesteric matrix. An investigation of the kinetics of the photosensitized back photoreaction of the photochromic molecules in the cholesteric mixture showed that the polarized energy transfer from the fluorescent groups to the photochromic diarylethene dopant caused an increase in the photoselection rate. The thermal stability of dichroism in films of the mixtures was studied and it was shown that the disappearance of the dichroism of the diarylethene molecules occurred with a noticeable rate even at room temperature.

Scheme of photophysical and photochemical processes under the indirect excitation of diarylethene molecules.

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Scheme of photophysical and photochemical processes under the indirect excitation of diarylethene molecules.
Preparation of Spherical MgCl2‐Supported Late‐Transition Metal Catalysts for Ethylene Polymerization
Authors: Xu Renwei , Liu Dongbing , Wang Shibo , Mao Bingquan
Published: April 2006

Summary: Facile and effective immobilization of late‐transition metal catalysts, 2,3‐bis‐(2,6‐diisopropylphenyl)butane diimine nickel(ii) dibromide (A) and 2,6‐bis‐[1‐(2,4,6‐trimethylphenylimino)ethyl]pyridine iron(ii) dichloride (B), for ethylene polymerization has been achieved, using spherical MgCl2 supports obtained by thermal dealcoholization of MgCl2 · 2.56C2H5OH instead of using supports of type MgCl2/AlRn(OEt)3−n. BET, XRD, IR, SEM, GPC, and DSC analyses indicate that the composition and structure of the supports, the activities of the supported catalysts, and the properties of the resultant polymers are strongly dependent on the dealcoholization temperature. The support SP‐3 obtained by treating MgCl2 · 2.56C2H5OH at 170 °C for 4 h is very effective for immobilizing late‐transition metal FeII and NiII catalysts. Compared with the corresponding unsupported homogeneous catalysts, a significant increase in activity is observed for the SP‐3 supported catalysts in ethylene polymerization, and the kinetics of polymerization is stable during the reaction process. In addition, replication of the support morphology is found in final polymers.

Kinetic profiles of ethylene polymerization using SPC‐4, SPC‐5, and SPC‐6 under 1.0 MPa and at 70 °C.

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Kinetic profiles of ethylene polymerization using SPC‐4, SPC‐5, and SPC‐6 under 1.0 MPa and at 70 °C.
Effect of Methylated Cyclodextrins on the Crystallization of Poly(3‐hydroxybutyrate)
Authors: Shin Kyung‐Moo , Dong Tungalag , He Yong , Inoue Yoshio
Published: April 2006

Summary: The effects of methylated CDs, α‐ and β‐DMCD and α‐ and β‐TMCD on the crystallization behavior of P(3HB) have been investigated by employing DSC and polarized optical microscopy (POM). The crystallization and nucleation of P(3HB) was improved by an addition of appropriate amount of each methylated CD, while negative effect of miscible blend was observed when the amount of addition exceeds the optimum value for the maximum nucleating effect. β‐TMCD was shown to be the most effective for the enhancement of the P(3HB) crystallization, thought to be due to the possibility of IC formation with P(3HB).

Plots of log{−ln [1 − X(t)]} versus log (t) for mixtures of P(3HB) with different CDs or talc, respectively.

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Plots of log{−ln [1 − X(t)]} versus log (t) for mixtures of P(3HB) with different CDs or talc, respectively.
Hollow Microstructured Polyaniline Prepared Using Cuprous Oxide Crystals as Templates
Authors: Zhang Zhiming , Deng Junying , Sui Jing , Yu Liangming , Wan Meixiang , Wei Yen
Published: April 2006

Summary: Hollow octahedrons or microspheres of polyaniline (PANI) were successfully prepared using cuprous oxide (Cu2O) crystals as new templates in the presence of H3PO4 and ammonium peroxydisulfate as a dopant and an oxidant, respectively. Interestingly, the hollow octahedrons (in the reduced form with a conductivity of <10−8 S · cm−1) could transform into conductive microspheres (in the emeraldine salt form with a conductivity of 10−2 S · cm−1) when the [APS]/[An] ratio was changed from 1:1 to 2:1. Compared with the common template reported, Cu2O crystal is not only a new type of template in terms of both shape and quality, but also omits post‐treatment due to soluble Cu2+ formed by the reaction of Cu2O with APS during the polymerization process. The universality of Cu2O as a template to prepare microstructured PANI was proved by changing the morphology of the Cu2O crystal. It was found that the morphology, oxidation and protonation state of PANI microstructures prepared with octahedral Cu2O as the template were affected by the [Cu2O]/[An] and [APS]/[An] ratio due to the competitive reaction of aniline and Cu2O with APS.

TEM images of PANI microspheres prepared using Cu2O as a template in the presence of H3PO4 and APS as a dopant and an oxidant.

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TEM images of PANI microspheres prepared using Cu2O as a template in the presence of H3PO4 and APS as a dopant and an oxidant.
Temperature and Pressure Dependence of the Free Volume in Polyisobutylene from Positron Lifetime and Pressure‐Volume‐Temperature Experiments
Authors: Kilburn Duncan , Wawryszczuk Jan , Dlubek Günter , Pionteck Jürgen , Häßler Rüdiger , Alam M. Ashraf
Published: April 2006

Summary: The microstructure of the free volume and its temperature and pressure dependence in PIB were studied by PVT experiments and PALS. Employing the Simha–Somcynsky equation of state, the hole‐free volume fraction h and the specific free and occupied volumes, Vf  = hV and Vocc = (1 − h)V, respectively, and their expansivity and compressibility were calculated. From the PALS spectra analyzed using the LT9.0 software, the hole size distribution, the mean hole size 〈vh〉 and mean dispersion σh were calculated. From a comparison of 〈vh〉 with Vf, the hole density $N'_{\rm h}$ was obtained. It was found that PIB shows an unusual thermal expansion with glass‐like transitions at 210 K and 290 K (at 0 MPa). A similar behavior is observed for tan δ. It was found that at 296 K, 〈vh〉 decreases exponentially from 80 Å3 at 0.1 MPa to the extremely low value of 10 Å3 at 1 300 MPa. Starting from a fluctuation approach, the free‐volume fluctuations and the characteristic length scale (ξ) of dynamic heterogeneity of structural relaxation were estimated from σh. It was found that ξ increases from ≈1.5 nm to ≈1.9 nm when the temperature decreases from 293 K to the glass transition temperature Tg = 207 K (at 0 MPa) or the pressure increases from 0.1 MPa to 200 MPa (at 296 K).

Fractional free volume and its mean fluctuation in PIB as determined from positron lifetime spectroscopy and PVT experiments analyzed with the Simha‐Somcynsky equation of state.

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Fractional free volume and its mean fluctuation in PIB as determined from positron lifetime spectroscopy and PVT experiments analyzed with the Simha‐Somcynsky equation of state.
Hybrid Nanocomposite Films from Mono‐ and Multi‐Functional POSS Copolyacrylates in Miniemulsion
Authors: Castelvetro Valter , Ciardelli Francesco , De Vita Cinzia , Puppo Antonio
Published: April 2006

Summary: The synthesis of aqueous dispersions of hybrid acrylic copolymer particles with either a monofunctional or a multifunctional polyhedral oligomeric silsesquioxane methacrylate comonomer has been performed by free radical heterophase polymerization. The miniemulsion process gives stable latexes, whereas the less controlled emulsion route results in colloidal instability of the products. The thermal and mechanical properties of the nanocomposite latex films have been preliminarily investigated.

The nanocomposite latex particles based on hybrid copolyacrylates with highly dispersed POSS cages.

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The nanocomposite latex particles based on hybrid copolyacrylates with highly dispersed POSS cages.
Unbalanced line characterization for differential‐mode operation
Authors: Agili Sedig S. , Smith Stephen B. , Balasubramanian Vittal
Published: April 2006

This paper presents a theoretical model of the differential‐mode operation of unbalanced pairs and a method for its characterization. A differential pair having temporal imbalance is characterized using S‐parameter representations. Measurements in the frequency domain are performed. These measurements validate the proposed theoretical model. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1169–1174, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21549
The design of a dual polarized QUASI‐YAGI antenna array
Authors: Aghdam Karim Mohammad Pour , Kamarei Mahmoud
Published: April 2006

In this article, the design of a dual‐polarized quasi‐Yagi antenna array is described. The quasi‐Yagi elements are fed by broadband microstrip‐to‐CPS balun. A feeding circuit that contains multiple Lange couplers is designed to feed a 2 × 2 array of quasi‐Yagi elements. A 30% bandwidth (1.4 to 1.75 GHz) is achieved for VSWR and gain. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1164–1169, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21550
Design of microwave lumped and transversal bandpass filter with noise reduction
Authors: Choi Wai‐Wa , Tam Kam‐Weng , Martins Rui
Published: April 2006

A simple design technique for a microwave lumped and transversal filter using constant‐k filter sections is presented. The noise figure can be suppressed by source degeneration inductors, which are added to the transversal element. The filter elements are analytically derived based on the specification and the noise minimization. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1161–1164, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21551
EMC internal patch antenna integrated with a U‐shaped shielding metal case for mobile device application
Authors: Su Chih‐Ming , Wong Kin‐Lu , Chen Brian , Yang Sam
Published: April 2006

A novel integration design of a shorted patch antenna and a U‐shaped shielding metal case for application in a mobile communication device is presented. The shorted patch antenna is mounted within the dented portion of the U‐shaped shielding metal case, which can provide a coupling‐free space for accommodating electronic components such as the RF modules/circuitry and battery in the mobile device. Thus, in this case, the shorted patch antenna can operate as an internal antenna having an electromagnetic compatibility (EMC) property with nearby electronic components. In addition, with the proposed integration design, the shorted patch antenna is isolated from the two side edges of the system ground plane of the mobile device. Hence, it can be expected that the effects of the user's hand on the performances of the antenna will be suppressed. The proposed integration design applied to a smart phone for Universal Mobile Telecommunications System (UMTS, 1920–2170 MHz) operation is studied. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1157–1161, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21552
Near‐field data compression for the far‐field computation in FDTD
Authors: Pascaud Romain , Gillard Raphaël , Loison Renaud , Wiart Joe , Wong Man‐Faï
Published: April 2006

This paper presents a technique to compress the near‐field data required to compute the radiated fields using FDTD. This technique is applied to the study of a UWB planar diamond antenna. The results show a 99.8% gain in memory storage, while maintaining good accuracy: less than 1% error on the far‐field radiation patterns. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1155–1157, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21553
A 3.5‐GHz low‐noise amplifier for first‐generation ultra‐wideband radio
Authors: Yang Li , Liao Huailin , Zhang Guoyan , Huang Ru , Zhang Xing
Published: April 2006

We present a fully integrated low‐frequency (3.1–5‐GHz) ultra‐wideband (UWB) low‐noise amplifier (LNA) which implemented with a Jazz 0.35‐μm SiGe BiCMOS (peakfT60 GHz) process. The combination of common base and resistive shunt‐feedback stages was adopted as the main structure of the designed LNA. The measured maximum gain is 15.7 dB at 3.5 GHz with 0.6‐dB gain flatness over the whole operating bandwidth. And the minimum NF 3.8 dB is achieved at 4 GHz. The whole circuit including the bias circuit network consumes 7 mA with 3‐V supply and only occupies 0.65 × 0.9 mm. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1119–1123, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21554
A pattern‐reconfigurable microstrip antenna element
Authors: Lee K. W. , Rojas R. G. , Surittikul N.
Published: April 2006

A novel radiation‐pattern‐reconfigurable circularly polarized microstrip antenna structure is presented. The measured results show that the antenna is able to provide a magnitude difference of more than 6 dB at 90° from broadside (in two principal planes) for the tangential (to the antenna surface) field component between the on and off states of the switches. Nonetheless, the vertical field component remains relatively unchanged. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1117–1119, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21555
Comparison between different models for the thin metallic substrate in multilayer microstrip structures
Authors: Zhang Lu , Song Jiming
Published: April 2006

The dispersive characteristics of multilayer microstrip structures with one thin metallic substrate are studied using the spectral‐domain approach. The numerical results of several approximate models are compared with that of the immittance approach as one exact model. The comparison shows that the widely used resistive sheet (R‐card) model is not appropriate to handle such structures over a broad frequency range. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1113–1117, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21556
New planar slotted‐patch resonator for miniaturized bandpass filter applications
Authors: Zhang Wen‐Jian , Li Zheng‐Fan
Published: April 2006

A new planar slotted‐patch resonator is proposed for RF and microwave bandpass filter design. The novelty of the proposed resonator is that it can reduce the size of the filter significantly. It is found that the resonant frequency of the resonator is reduced (for example, by 61%). A dual‐mode filter operating at 2.39 GHz with 1.7% bandwidth and a three‐pole bandpass filter operating at 2.375 GHz with 8.8% bandwidth are designed and fabricated. The measured results agree very well with the full‐wave EM simulation. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1110–1112, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21557
MIMO space‐time coding for diffuse optical communication
Authors: Garfield Matt , Liang Chao , Kurzweg Timothy P. , Dandekar Kapil R.
Published: April 2006

A multiple input, multiple output (MIMO) diffuse optical communications link is implemented and evaluated using a 2 × 2 Alamouti‐type space‐time coding scheme to increase link performance beyond that of single input, single output (SISO) and multiple input, single output (MISO) systems. We present a representative profile of received power versus distance, and comparative bit‐error probability performance. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1108–1110, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21558
Application of differential evolution algorithm to the modeling of laser diode nonlinearity in a radio‐over‐fiber network
Authors: Akdagli Ali , Yuksel M. Emin
Published: April 2006

In this paper, a simple and efficient method based on the differential evolution algorithm (DEA) is applied to the problem of modeling nonlinear characteristics of microwave intensity‐modulated laser diodes used in a radio‐over‐fiber (RoF) network. The performance of the presented method is experimentally evaluated using two different laser diodes. Very good agreement between the experimental measurement data and the model output indicates that the presented DEA based method may efficiently be used for accurate modeling and computation of IMD3 power levels of microwave intensity‐modulated GaAlAs diodes. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1130–1133, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21560
Low‐loss DPDT‐switch configuration with DGS structures
Authors: Thakur Jay Prakash , Ahn Ka‐Ram , Jung Myeong‐Sub , Jang Byoung‐Jun , Cho Hong‐Gu , Park Jun‐Seok
Published: April 2006

In this paper, a DPDT (Double‐Pole Double‐Throw) switch with defected ground structure (DGS) is newly proposed for transceiver systems. A biased varactor diode is introduced to control the on/off operation of the proposed switch. In order to confirm the validity of the switch, we design and implement the switch at the 2.45‐GHz frequency. It is designed specifically for antenna‐diversity switching for WLAN applications. The experimental results show very low insertion loss, excellent power handling, and high isolation performances. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1127–1130, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21561
In‐line beeline CMRC and applications to compact microstrip low‐pass filter
Authors: Zhang Fei , Gu Congying , Shi Lina , Li Chengfang , Gu Jiangzhong , Sun Xiaowei
Published: April 2006

A novel beeline compact microstrip resonant cell (BCMRC) is proposed in this paper. Its photonic bandgap and slow‐wave effect are evaluated. The compact configuration presents superbroad stop‐band and improved slow‐wave characteristics. A low‐pass filter, consisting of three BCMRCs connected in series, is designed and fabricated. The filter has the advantages of low insertion loss in the passband, sharp, high, and wide rejection in the stop‐band, and compact size. Good agreement between the experimental and simulated results is achieved. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1125–1127, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21562